Format code tag that literally means "Replace this by a string of characters". Orinigally introduced in the C programming language as a format specifier for the printf function, it was later adopted by a plethora of other languages such as java, ruby, etc.

What you get when you click the Urban Dictionary quick search found in the firefox bookmarks. Check out your bookmark manager, and it'll tell you how to use it, They are just pointing it out to you. If you type "slang " and then whatever you want after the space, it will search that in urban dictionary.

%s is what appears when you click on the Urban Dictionary link in Mozilla Firefox.

This is because it's a special type of bookmark which lets you type the word "slang" followed by a slang term, and it will automatically look it up for you in this fine dictionary.

You can also use the words "google" (google), dict (dictionary.com), "wp" (wikipedia), and quote (stock market prices).

What you get when you click on Urban Dictionary in Quick Searches in
Firefox bookmarks...

1)In typing and typeset the symbol in question is the percent sign and when followed by lower case s, as if attached, indicates that it represents multiple percents