Can someone explain frames and frame data to a dummy(me)?
Frames is a measure of time in fighting games (and in other games). SFV runs at 60 frames per second, so one second is 1/60th of a second.
Every move has 3 basic properties and then additional properties based on what happens if it gets blocked, it connects and it hits as a counter hit (plus other parameters).
Basic:
Start up: How fast the move comes out and then hits the opponent.
Active: How long the move lingers on to hit the opponent (how long it is "active)". In practical applications, think of a lightsaber having a ton of active frames because you can be hit during any portion of its attack.
Recovery: The recoil or refractory period after an attack hits. You can't do much during this part of a move.
A move that has low start up (comes out fast), is active for a long time (lingers) and has low recovery (less recoil) is a move that is very powerful provided the hitbox/hurt box are good too (a separate thing entirely). A good example is something like Zero's light saber attacks in Marvel 3 or Frank West's Chain saws.
If a move has 10 frame start up then you can beat it with a move that is 9 start up frames or less in start up provided that you both hit the button at the same time. If a move has 10 frames of recovery, then you can punish it with a 9 frame start up move or less. And so on.
Things get more complicated when block stun and hit stun are added to the equation. Block stun is how much frames the opponent is "stuck blocking" in after they block an attack. So you make someone block with a heavy attack like Bison's st.HK, you will notice that it locks the opponent in place for quite a while when the block.
This leads to something known as block advantage/disadvantage. This is generally a relation of recovery to block stun of a move. If a move recovers fast AND has a lot of block stun, then it means that you will recover before your opponent comes out of block stun. Again going back to Bison's st.HK, if you combine the recovery of the move and its block stun... you will recover 3 frames before the opponent does meaning it is +3 on block and that means if both Bison and the opponent presses a 5 frame move... Bison's will win out because his would've come out 3 frames earlier. This is what leads to frame traps in the game and counter hit set ups. Usually in frame data, we don't list block stun because what really matters is the block advantage/disadvantage (though in other games with more complex mechanics, knowing block stun frames is sometimes relevant).
Hit stun is similar to block stun and happens when you hit the opponent with the move. They reel back from the hit for a certain amount of frames, we call this hit stun. Let's take Bison's st.MP attack now. On hit it has 6 frames of advantage. That means that if I can follow up with a move that is less than that, then it will combo (provided I am in range). Again the concept of recovery vs hit stun applies here... Bison's st.MP hits them with enough hit stun and recovers just in time to have 6 frames of advantage. So just by looking at the frame data, I see that Bison's cr.LK has 4 frame start up which means I can easily follow up his st.MP with a cr.LK for a combo.
If you hit someone as a counter hit (hit them during the start up of a move) then you will usually have more hit stun on their move. In SFV, I believe there's a flat +2 hit advantage on all moves that don't have a special property. Going back to Bison's st.MP, it has start up of 7 frames and a hit advantage of 6 frames normally. That means that I cannot combo st.MP into st.MP because 7 frames is 1 frame too slow to combo after it. However, if I hit them on a counter hit with st.MP... that gives me 8 frames of advantage which means the second st.MP at 7 frames should now connect. This is where counter hit set ups and combos come in. It's a bit more advance but not a difficult concept to understand. Some moves have special properties on counter hit ie. crush counters and they have a certain amount of additional hit stun to them.
Frame data gets muddier when cancels are involved. Cancels can by pass recovery frames of a move, allowing for combos that may not be possible through regular linking (ie. waiting for a move to finish before starting up the next move). Bison's cr.MP only has 3 frames of hit advantage and if you tried to link into his LK Scissor Kick special it would be impossible to do so as the Scissor Kick has 15 frame start up. However, if you cancel the cr.MP into the Scissor Kick it will combo because recovery is taken out of the occasion mostly. Remember that hit advantage is a combination of hit stun and recovery.. not just hit stun.
Hope this helps.