I can see some moderators editing posts here... These moderators have little reputation points such as 100 approx. and few silver and bronze badges.
I wish to know what it takes to be a moderator on Ask Ubuntu or the Meta site.
I think you're talking about these two recent posts:
These were edited by Shog9 and Adam Lear. These two guys are Stack Exchange employees, so they have network-wide phenomenal cosmic powers and mod diamonds everywhere they go. They don't have much rep on Ask Ubuntu, since they haven't used this site much. However, they have lots of rep on other sites in the network. They became employees after contributing outstandingly to other Stack Exchange sites.
SE employees tend to drop by when any site's child meta gets a question tagged bug or feature-request since if there really is a bug they'll have to fix it, and if a feature request is to be implemented, they'll have to implement it. They often edit the tags on those posts to indicate the status of the report/request, though site mods also handle many such posts if there's no need for attention from employees. Only moderators can add the red status tags. You're also likely to see employees around when there is a moderator election.
The election of moderators is explained in this page of our Help Center. On new SE sites, mods are appointed by SE employees, but on mature sites, they are always elected by popular vote.
A humble ordinary moderator(!) rather than a Stack Exchange employee will in general have a lot of reputation and badges and suchlike on the site where they are a mod, since many members of the voting community are likely to interpret these as a measure of a user's contributions and commitment to the site. All our Ask Ubuntu moderators have many reputation points and badges.
A moderator on a site like Ask Ubuntu is also a moderator on that site's child meta, as you'd probably expect. There's no way to become a moderator only of a child meta.
What you're referring to is probably editors and it takes 2000 rep to become an editor.
On the main site, if the user is a few 100 rep, he's just a user that has to go through a review process before his/her edits are approved.
On Meta, only 2000 rep users can edit as per Zanna in the comments.
For all privileges and the rep they need look here
I'm not a moderator: moderators have a diamond next to their name like
What it takes to become a mod is: Being elected.
There are also
rep whores very high rep users like this one that just want to be a user and do not want to be a mod.