Balance transfer questions

I have a quick question on balance transfers as I have never done one! When it say “12 months at 0% APR, for 12 months, on transfers made within 60 days”

Is that meaning if let’s say I do a transfer in the first 60 I have no fee or maybe the 3% fee depending on the card. BUT if I made a transfer on say day 90, I would have the normal 5% transfer fee, AND that money would then not be interest free?

I’m just confused on the verbiage. I’m probably not wording it well. But let’s say I make a transfer after that 60 day window, is that going to be charged interest, or just the higher transfer fee but not have interest that introductory period is over?

Any help is appreciated! Thank you

If it helps, let’s say the Amex blue cash preferred, or the Chase Slate