The intended (and, in fact, widely understood within mathematical community) meaning of that statement is whether the roots of polynomials can be expressed usi

The intended (and, in fact, widely understood within mathematical community) meaning of that statement is whether the roots of polynomials can be expressed using radicals, ie. as algebraic expressions involving four standard arithmetic operations and taking roots. I’d rather quibble with the part where they say that this is “immediately” seen from Galois group, as showing solvability of a group is not trivial matter at all.