expression
even if I say; even if I tell you
Colloquial contraction of 言ったとしても. Used to express that even if one says something, it won't change the situation or the listener's understanding.
今さら言ったって、もう遅いよ。
Even if I tell you now, it's already too late.
本当のことを言ったって、誰も信じてくれないだろう。
Even if I tell the truth, no one will believe me.
Contraction of 言った (past form of 言う) + って (casual quotative/conditional particle), equivalent to 言ったとしても.