Verbs ending in -ся/-сь are traditionally called reflexive verbs. However, not all such verbs have a reflexive meaning (like ћн мІлся 'he washed himself): some have a reciprocal meaning (like онќ вќделись чђсто 'they saw each other often), some have a passive meaning (like учљбники продаєтся здљсь 'textbooks are sold here'), and some don't seem to have any particular categorical meaning at all.
If you want to find out what a reflexive verb means, you must look it up in a dictionary. The one thing they all have in common is that they are intransitive (they don't take an accusative object).
Some reflexive verbs pair up with non-reflexive counterparts and some don't. In the Examples section, we list some reflexives along with their non-reflexive counterparts. Though you can't tell for sure how adding -ся to a verb will affect its meaning (sometimes the meaning is radically different), you can make an intelligent guess.