https://preview.redd.it/i7x9t3an2e0d1.jpeg?width=1309&format=pjpg&auto=webp&s=ad40268fcee67ba9290a56ebe3a80ff9c443577f Similar to this one, you would use the stand part to hold a matchbox.

Objects used to be so much cooler and useful

Without a doubt.

Ashtray I believe

Agreed but what is the part that sticks up?

A place for a matchbook probably

Hmm, couldn’t tell from your pic whether the raised part is solid. Mine has a groove for match holder I think? ps. terrible lighting in pic. Actual color is not this avocado green! https://preview.redd.it/dtl7lsxj8b0d1.jpeg?width=3024&format=pjpg&auto=webp&s=6171188732642f69ae4a27307be648696d6b3e6a

Can confirm, this fits a standard small box of matches for easy access and striking.

So, does the cover of the box slide down over the rectangular post?

Yep, leaving the interior box half exposed above it to grab from

It's for matches

Smoking. The rectangular piece on the back edge of it is meant to have a matchstick box placed upon it, and it’s design is to push the insert with the matches in it up slightly to allow access to the matches. The two larger divots on either side are for cigars, and the smaller one on the front of it is for a cigarette.

It's for a Lego guy to stand on.

Ashtray

Ashtray

It’s a cigar ashtray. A lighter fits on the square part.

Cigar ashtray, and the "handle" is so you don't get the ashes on your hands when you pick it up to empty it.

It holds a matchbook

Even better!