What is the ruling on someone who swore several oaths and broke them years ago, and does not know their number, and how should that be expiated, and is it permissible to fast the expiation for an oath on Mondays and Thursdays?

A Muslim should avoid swearing excessively. The expiation for an oath is feeding ten needy people, or clothing them, or freeing a slave. If one is unable to do these, then fasting for three days is required. The fasting may be done consecutively or non-consecutively, though consecutive fasting is better.