[Grammar] Use of pronoun "they" for "someone" "a person"

Hello,
I have always wanted to know if it is right to use the pronoun "they" to refer to the subject "someone" or "a person". I have seen it used in that way in some texts, but I am not sure if that is acceptable in standard English.
For example:
"If a person is not sure about what to do, they should ask a supervisor".

thanks for your advise.

Welcome to the forum, appf. :hi:

Except in more formal speech or writing, many people use 'they' nowadays, and not many object. For most of us, it's far more natural than 'he or she'. Some of us avoid the problem when we can by using plural forms:

If people are not sure about what to do, they should ask a supervisor.