The product of the two transpositions is a 3-cycle, so the subgroup contains both transpositions and 3-cycles: it fits in no proper subgroup and is all of \(S_3\), with 6 elements.
The subgroup generated by a subset \(S\) of a group \(G\) is the smallest subgroup \(H\) of \(G\) containing \(S\); it is denoted \(\langle S\rangle\) and \(S\) is called a generating set.