What is this going around my Ford cargo van?

So i have been thinking about repairing some rust spots and noticed that there was the 5 inch or so that bumps almost going around the bottom of the vehicle and wasn't sure if i need to get buy something to get that texture? Hard to explain is anyone able to help please?

Added (1). Anything i can do to get the texture? Or Anything i can buy?

You have been infested by metal worms.
You will need more than a can of touch up paint to fix that.
The bumps are from a previous bodged repair.
Are you sure the vehicle is roadworthy?

That is a textured material applied before the body is painted. It is intended to hide the small impacts caused by small stones and other debris from the roadway.

There's a Rustoleum spray paint that will turn into that textured finish when you spray it.
You're only going to make the rust look better- have the entire undercarriage checked for important rust. That's a significant amount, and you may not be able to get an inspection sticker. You could also have structural damage.

See a body shop. Your van needs to be repaired.

Just fix the rust. Don't worry about the texture of the paint. If it bothers you, just spray on the paint top coat extra thick so you get orange peel effect, but unless you are doing a full restoration and you want the van looking just-left-the-factory-immaculate, I would just leave it however it turns out.

It is an anti-chip coating applied before it was painted. Auto paint stores sell it