“One’s” has two uses in English. The first use is as a contradiction of “one is”. The second use is the possessive pronoun of “one”. “Ones” is the plural of “one” when the name of the object is not used.
“One’s” has two meanings in English so we need to talk about them separately.
When “One’s” means “One is”
“One’s” can be a contraction of “one is”.
“One’s” is used when we use “one” with the verb to be or to have.
One’s more than none. (One is more than none.)
No one’s paying attention. (No one is paying attention.)
This use is much more common in spoken English.
When “One’s” is the possessive pronoun of “one”
“One’s” can also be the possessive pronoun of the pronoun “one”
“One” is a subject pronoun that we use when we don’t want to talk about a specific person.
One loves to go out at the weekend.
When we need to make this pronoun possessive we use “one’s”.
One’s health is one’s wealth.
“Ones” is the plural of “one” when one is an unnamed object.
Think about when we have an option to choose between different options that are similar. We say “this one” or “that one” because the name of the object is not important(because it is obvious).
When we need plural demonstrative pronouns(this, that, these, and those) we use “ones” instead of “one”.
How do you use “ones” in a sentence?
We often use “ones” with “which”,” these”, or “those”.
Which ones do you want?
Do you want these ones or those ones?
Remember, when we use “ones”, it must be obvious from the context what we are talking about for example when you are pointing at different things.
What about “the ones”?
We can also use “the ones” when we are trying to bring the attention of someone to a particular object or objects.
Which ones do you like?
I like the ones with blue laces(in this case it is shoes).
Ones’ is not common in English. This situation would have to be a possessive of the plural of one(ones). Something like the shoes above.
These ones’ laces are really nice. (again, we are talking about shoes)