We call this in Arabic : ألف مقصورة It is a way to write letter ( أ ) in the end of some words , especially in some adjectives

It's almost like a(ا) in English(a) and always comes at the end of the word

This letter ى ( ya' ) is pronounced ( ya' ) if it has 2 dots ex : يجري ( yajree ) and it is pronounced Alif if it is free of dots ex : على ( ala ) - إلى ( Ela )

ي but it doesn't have the dots and it sounds like alif, so what is it?

This letter "ى" is indeed a "ya'" "ي" , most natives actually never use the dots with the "ya" anyway, so don't rely on the dots too much. Now, when you find a "ya" "ى" at the end of a word where its pronounced as "alif", it's what is called "alif maqsurah" "ألف مقصورة" (restricted alif), also called "alif layyina" "ألف لينة" (flexible alif), which is a special case where you have an ending "alif" that is written as "ya", still pronouned as "alif". Tell me if you want to know more details about when is the "alif" written as a "ya".