C# is Microsoft's answer to Java. It's designed to be a flexible and easy to use language. C and C++ form its base but those languages allow for much more complexity and in turn, are more complex themselves - and being relatively old, aren't as efficient as they could be. At the same time, there are things that C# is better at. Compiling is faster and you often write less code for the same results, for example.
As for what to start with, I'd say BASIC might be a good one to examine when you start, being as simple as it is, but most courses will start you on Java or possibly C# before moving you onto C+, etc. My advise would be to look through some simple BASIC programs and see how they're structured, what the different calls and functions, etc do and get somewhat familiar with the logic behind code but to focus the best part of your efforts on C#. Once you've got one language down, it gets a lot easier to learn another as the majority of them have their similarities.
The difference between a low-level and high-level language is abstraction .i.e. A low level language speaks to the processor itself whereas a high level language is designed to be understood by a human with some level of expertise. An example of a low and high level language would be Machine code (at it's simplest, just binary) and C#, respectively. Since a low level language is coded for the processor itself, it's a good solution for high performance, memory-stingy programs as you can achieve great precision with little errors, as well as allowing the deep control that speaking to the processor itself allows. The downside to this of course is that it's not easily understood by a human, calls for detailed knowledge of how a particular architecture or system works and is vastly more time-consuming when compared to a high level language like C#.
Don't be scared by the syntax. Once you start learning what everything means and how you can use it, you'll start to see the logic of it all. Microsoft has readily-available and comprehensive tutorials on how to use C#, as does Oracle for Java but it might be useful to pick up a book such as one from the Head First series.