This is the 13922nd most frequent Spanish word.
soltero
Unmarried; single.
In this sentence, 'solteros' is used as a noun referring to individuals who are not married.
Es una fiesta exclusiva para solteros.
It is an exclusive party for singles.
Here, 'soltero' is used as an adjective to describe a marital status, meaning 'single'.
Soy soltero y disfruto de mi tiempo libre.
I am single and enjoy my free time.
Here, 'soltería' is a derived noun form of 'soltero', referring to the state of being single.