hello, the strength marks are:

F-strong, FF-very strong, fff--- heavy strong, sf--- extremely strong, mf--- medium strong, very strong.

p-weak, PP-weak, ppp--- heavy weak, sp--- extra weak, mp--- medium weak, spf extra weak and then strong

In contemporary music, there are also ffff, pppp and even more

The strength mark itself does not define how loud it is, just to reflect a comparative relationship.

If you still don't understand, please reply and answer at any time. Thank you ~