Gaseous form is a spell that turns a willing creature into a gas cloud.
The spell gives resistance to damage, ADV to some spell saves, and the ability to travel through tiny cracks to get somewhere.
Like many spells, unless it explicitly says something, it is up to the DM. Other things you can do with it:
- take dodge, search, dash, or help actions
- Appear out of a cloud for a surprise attack
- get past traps
- be transported in a large jar or container
- move via a draft or wind
- change your shape (but not your size) in any way
- intimidate others
- see in all directions
- communicate telepathically