Based on it being an EN steel grade:
The first number is 100x the carbon content percentage (so 0.11%), the letters are added elements (sulphur and maganese), and the last number is the sulfur content (0.30%). You can see the full details here.
The full format seems to be:
[X][% carbon][added elements][% of added elements, hyphenated]
Note that the X is only present for stainless steels. Here is a good example.
Note also that this scheme is somewhat ambiguous. The percentages are only an approximation, and the example you gave is interesting because it lists Sulfur before Maganese, despite the naming convention stating that they should be listed in order of content.
That's alright for getting quick basic info about the steel, but for anything else you may want to use the EN number, 1.0715, rather than the name. Wikipedia has details on the format. Given this classification you can find out much more about the steel's properties and see what general category it fits into. The site I linked first says this:
EN 10277-3: 2008 Bright steel products
Technical delivery conditions. Free-cutting steels
EN 10087: 1999 Free cutting steels
Technical delivery conditions for semi-finished products, hot rolled bars and rods