boostorg/geometry

@rachitmanas
R-tree is a hierarchical data structure used for n-dimensional (spacial, nearest neighbour) searching, just like e.g. red-black-tree is a data structure used for 1-dimensional searching of keys/numbers typically used to implement e.g. std::set and std::map in C++. There are many other spatial search data structures besides R-tree, e.g. KD-trees, Quad-trees, Octrees, etc. There are many variants of each of them, many ways of creating them, etc. The principle is the same as with 1-dimensional trees or std::binary_search, to make the computional complexity of an algorithm lesser if possible.
WKT is one of the text representations of geometry data. Is a way of defining points, polygons etc. in text format. We use this one primarily because it's the standard one defined by the OGC SFA (and SQL/MM Spatial) standards. These standards are the golden standards in the domain and implemented by spatial DBMSes like PostgreSQL/PostGIS or MySQL.

Is this library way too advanced for someone like me?

It's hard to tell because we don't know you. You have to decide for yourself whether or not something is to difficult for you. If computional geometry is something new for you then you have much to learn. As it is the case with all other domains.