学校の先生もとても優しいです
What does the first "も" mean?
It is hard to be 100% sure without context, but this も is probably an inclusive も, as in "also".
So something like "The school teacher is also very kind". But you need to be careful with this translation because the "also" applies to the teacher, not to kindness.
For example: "Bob is kind. Alice is also very kind." ボブは優しいです。アリスもとても優しいです。
[Also note how the も "replaces" は (which itself "includes" が) so as a case marker it carries all three functions "additive", "subject", and "topic".]