what is one and ones?

it's the difference between a singular (i.e. 'one') and a plural (i.e. 'ones'). use one/ones to avoid repetition避免重複. compare:

(1) I need a camera. Can you lend me ONE (=THE CAMERA)?
(2) The men in the screen are THE ONES (=THE MEN) I saw last night.

one = an individual
ones = a group of individuals

Examples:

1. Mary, you are my love one.

2. Girls, you are all my love ones.