Helpful resources for general purpose C++ :)
https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines
Bartek's coding blog
Discussions, articles and news about the C++ programming language or programming in C++.
'C++ Weekly' channel.
CppCon conference videos.
A Tour of C++ by Bjarne Stroustrup
Beginner friendly, does not assume prior knowledge of C++. https://the-eye.eu/public/Books/IT%20Various/ADDISON.WESLEY.A.TOUR.OF.C.PLUS.PLUS.2014.pdf
Effective C++ by Scott Meyers
Is helpful to improve your existing knowledge of C++. https://doc.lagout.org/programmation/C/Addison.Wesley.Effective.CPP.3rd.Edition.May.2005.pdf
Offers a list and a small introduction about C++ new features https://github.com/AnthonyCalandra/modern-cpp-features