I was recently asked this question and here is my answer:

This is a truly eternal question.

Humans have likely been pondering on this question for countless generations and likely will for countless more.

Isn’t this humbling? Amazing? Exciting?

It also probably means that this question doesn’t have any ready answer.

It possibly means that time is a story, one that gets retold in different ways by different cultures.

There may thus be no single truth.

Yours answers are thus as valid as anyone else’s.

You get to decide what time means to you.

This article explores some common ways humans see time: How Do I See Time?