How do you value an equity stake offer?

I am so out of my element here, so please forgive any ignorance or basic understanding on my part. I am being poached by a start up with roughly 35-45 employees. They are interested in me joining them and floated the idea of a c-suite title and roughly 2% equity share.

Now, the official interview is next week and I do not have an offer in hand. I just want to be prepared for if/when an offer comes.

I would have no clue what 2% equity would equate to in terms of an actual value. And I don’t know the first steps in making that determination. The company is only 6 months old, if that matters. What are the commonplace documents/financials that one could request in this circumstance, if any? They mentioned a larger company we both work with had interest in acquiring them. I can’t just ask them that number, can I? What would etiquette allow in such situations?

Any and all help would really be appreciated. I feel I am in over my head.

To be clear, talks were for a complete compensation package that includes salary, bonuses, benefits, and equity.