'Invincibility frames are the period of time (measured in frames) during which a character cannot be damaged. Depending on which kind of invincibility the character has, the attack may "hit" or "miss".'
I believe the term/spelling 'eframe' is wrong. There are indeed some skills that have built in 'timing' where they cannot be affected by anything. Those are called iframes. Which are completely normal. Now when you're not able to properly time your skills after the evade skill (iframe ending), it is because of lag. It is the response time calculated between your action and the transmission of your demand to the server. Same for your opponent except that in the relation of you to them, it's called desync.
There are skills that are evasive but not iframes. Such as any dashes or swaps like 1 for summoners. Those, your character is traveling and if you time your skills properly, you can cancel them.
There are also skills which make your character completely invincible while the skill is in effect and sometimes a little bit after depending.
Finally there are skills that have a built in frame where the character is unable to be attacked. That's an iframe. For example some skills starts with an invincibility frame but after the frame is done, you're able to stop it. Those kind of abilities needs to be timed right to avoid dmg with because not the whole animation will avoid dmg.
Hope you understand better what exactly the term means and why it applies to BnS in particular <3