Ask Rate
The minimum price at which a seller is willing to sell an investment or asset at a given moment. Also known as the offer price.
The ask rate can be fixed, which means that the seller is never going to change it no matter what. It also can be negotiable, which means that the seller might be ready to lower it a bit depending on the context.
Let us say that you are checking the EUR/USD value. You found that its current ask rate is 1.1050. 1.1050 is the rate that sellers are willing to sell the Euro against the U.S. dollar for now.