After the Jump
Just like how there are four Pre-Jump Frames at the start of the Jump, every character has four “Landing Frames” when they land from a Jump. However, how these four frames behave really depends on one factor: whether or not you perform a Normal Move during your Jump.
First of all, regardless if you attack in the air with a Normal Move or not, the Landing Frames will always prevent you from performing any form of basic movement. You cannot cancel the Landing Frames with a Dash, a Crouch, or another Jump. However, you can always Tech Throws during your Landing Frames.
However, you are allowed to cancel all four Landing Frames with pretty much anything else if you do not perform any Normal Moves during your Jump. Special Moves, Super Combos, Focus Attacks, Throws, and even Normal Moves can all be performed the instant you land. And most importantly, you can Block during the Landing Frames. That means if you do not press a button in the air, you cannot be punished when landing from a Jump even if the opponent makes you land into their attack.
So what happens if you do perform a Normal Move in the air? If you do, the first two of the four Landing Frames are actual, genuine delay frames. You cannot do anything during these two frames, not even Block (though you can Tech Throws, still, as mentioned earlier). Thus, opponents can punish you upon landing. However, the last two Landing Frames grant you the ability to Block, you still cannot perform a Special Move or a Super Combo or anything during those two frames.