Means “to your taste.”
Sometimes you’ll see my recipes have a “TT” written in the amount column. It stands for “To Taste.” It’s a fancy shorthand a chef (and cooks) uses to state that the amount in the recipe is not quantifiable, and is usually used for seasoning.
An example is in a recipe for carrot soup. You may have seen recipes out there that call for a static amount of salt like 1 tsp, but perhaps the carrots are a bit woody and need a bit more salt to perk them up? Do you really only need 1/4 tsp ground pepper?
Instead, I use the term “TT” to state that it depends, and I will need to taste the item. (Now you see why it says, “To Taste”)