7rl

OK. Here we go.
Short answer - That's the Irish version of "etc."

... but not exactly.

Long answer

First of all, "etc." is short for "et cetera", Latin words that mean "and so on". They used to write that Latin word "et" like a 7. We use Latin contractions in English because we think they make us look all official and stuff. No, really, we have a lot of other small words from Latin in English, like "vice versa" and "per capita". But, yeah, what does that have to do with this site?

Agus Araile means "and so on" in Irish. They take the s from agus, and the r with the l from araile to make their contraction. That gives us "srl."... OK!? : ) ... OK?!... Why is everyone still just staring at me like that?!
OK! What is that 7 there for??

Technically that's not a 7... anymore... Well, It never was, but we, like the Irish, are now using the symbol 7 to represent something else. When the Irish write srl., they use an older form of the s there. If you know about fonts, then you'll know what a seanchló font is, ... and if you don't, then you will in a couple seconds. It's an old Irish typeface - the kind you see on old signs and monuments and newer things that are trying to tell you, "Hey, I'm typically Irish". The thing about a seanchló font is, one form of the s looks like an r with it's vertical stroke descending slightly below the line. Want to see what it looks like? .... Google it. The other Roman alphabet using languages used to have something somewhat related to this from Latin "et". Look at the American Declaration of Independence. Here and there you'll see what looks like an f where an s should be. Well, that's not an f, it's another form of s that we don't use anymore. When written by hand the Irish version can look like a 7 with a shorter horizontal stroke and a longer vertical stroke.

And, ta daaaa - 7rl.