This is pretty self explainatory. The more difficult the language, the harder it is for a beginner to master. A language like Python is beginner-friendly language, whereas C is more difficult to start off with.
Front-end languages, like HTML, CSS, and Javascript, are what is seen in a website.
Back-end languages, like Java and Python, are what controls algorithms, background operations, logins, and more on websites.
Despite what it sounds like, high-level languages tend to be the easier of the two. This is because they are easier for people to read, or further from binary. This comes at the cost of either being harder for the computer to read, or requiring to be compiled (see below).
On the other hand, low-level languages are faster and easier for the computer to run, because they are written closer to binary. The downside to this is that these languages are a lot harder, especially for beginners.
Interpreted languages are languages that you can simply write and run, like Python.
Compiled languages are languages that you have to compile to a binary file before running. This makes it easier for the computer to run. An example of a compiled language is Java.