Scratch says I have been invited to curater for a Studio. But I don't know what this means.

It means you have been invited to a studio.
If you accept the invite, you will have the power to add projects to that studio ( if its set that not everyone can add projects ) and the studio displays on your profile on the “Studio I Curate” section.

A “Curator” is someone who is a member of a studio… They can add projects, and be promoted to manager. The word “curate” means to collect and assemble, so the idea is you can help curate projects. It can be relating to a theme, a hangout, or something else entirely!

If you are interested in curating, you can join the studio. But don't feel any pressure; you can reject it or leave a studio at any time.

Thank you.

Keep in mind that if you curate a studio, you'll recieve messages from that studio as long as you're in there.
Some studios will let you add projects only if you are a curator. If you are a promoted to a manager, you can add other curators and delete your own comments in the studio. If the host transfers host powers to you, you can also change the title, thumnail, and description. You can remove yourself from a studio by finding your name in the curators list and clicking the three dots, but you'll need to be invited again in order to join.
That's the basic rundown of how studios work

“Curate” means to select and organize items
So if you are curating a studio you are helping select and organize the projects for that particular studio.

(Some info I think that will be helpful):
If you accept the invite you will get notifications from that studio (unless you leave), this also applies if you follow a studio.
The host can select “managers” managers help manage the studio and have the power to delete projects, delete scratchers or add them.

There is also front page curators, who help select and organize projects that are on the front page of scratch.

Curate in Scratch means that someone has made a studio (a place where you can comment and add projects), and invited you to join!

If you accept the invite, you will become a curator, and get to add projects more easily! Hope this helped! (⁠・⁠∀⁠・⁠)

~OctopusGhost