GIVE ANSWERS - Español

the Spanish expression ”Eso sí” (notice the ortographical accent) is literally ”That yes” which is equivalent to say, ”yes indeed”
You would be agreeing with what was just said or asked by the other person.

You could use it to show you are accepting a previous argument just mentioned to you, like showing that you are now realizing that argument as true, like in ”Oh really, that’s right”

But it can have a slightly different use in other circumstances.

You could say ”something something, eso sí [some caveat you want to emphasize about what you just said yourself]” its is a kind of alternative ”but”.
-Come to the party, BUT don’t forget to bring your wine.
-Ven a la fiesta, ESO SÍ, no se te olvide traer tu vino.

”Así es” on the other hand is more akin to ”it is thus” or ”it is like that”, which could also replace ”yes indeed” , but this one is always affirmative to what was asked, and would not have the idiomatic uses from above.