Nを ください is an expression used to ask for something. The word indicating quantity or amount wanted is put right after the phrase Ｎを. The quantity/amount can be expressed by using the "number + counter"(e.g., 一まい[one thin and flat object], 二ほん[two long and cylindrical objects]), or words such as すこし[a little bit] and たくさん[a lot].
きっぷを 一まい ください。
Give me one ticket, please.
りんごを すこし ください。
Please give me some apples.
Particles are not used after words which express quantity/amount.