I just bought this water tank really cheap. But it doesn’t have a valve or anything on it. Just a hole. I want to put a valve on it and connect a garden hose to it. I’m sure they sell one, but I’m not sure what it’s called. Can anyone tell me what I’m looking for and where to buy it? Thanks.

You need to install a bulk head fitting on the bottom then add your valve. I'm not sure what your using it for but a 1" should be plenty

If it's a sprayer tank (and appears to be) measure the hole and go to a farm supply for the nipple.
As coldtrail called it "bulkhead fitting". It'll have a rubber gasket to seal inside. You'll need to find a skinny kid with long arms to assist you. 🤔

Thanks! I knew someone on Aldeer would know.

You can use a string run it through hole to the top of the tank and pull it through. I've installed many on large tanks at work.

I've used a paint roller handle or sometimes a piece of pvc conduit.

$12 on ebay with a screen. https://www.ebay.com/itm/302606085496

Look at Ag Spray. They have a bunch of fitting, etc.

Tractor supply has them on the shelf if nobody else local to you has them.