Se is a pronoun with many uses. I just finished reading The Nine Uses of Se from El Blog Para Aprender Esapñol. This is a wonderful blog. Raquel and María are Spanish teachers based in Madrid who give Spanish lessons via Skype. They also share lots of wonderful information and videos for Spanish students.
Here is a very, very brief summary of the EBPAES post.
1. Reflexive Se
Reflexive verbs are generally used when talking about the body, clothing, or feelings.
Mi hija se peina en el baño. (She combs her hair in the bathroom.)
2. Pronominal Se
Some verbs only have a reflexive form. A non-reflexive form does not exist.
arrepentirse – to regret Se arrepintió de decir eso. (He regretted saying that.)
3. Reciprocal Se
This form is used to express each other.
Se pelearon porque no se entendían. (They fought with each other because they did not understand each other.)
4.Some verbs have a reflexive and non-reflexive form. These verbs change their meaning when used reflexively.
admirar – to admire admirarse – to be amazed
5. Se as an Indirect Object Pronoun
Ella se lo da. (She gives it to him.)
6. Emphatic Se
¡Se pasó la noche conduciendo! (She drove all night!)
7. No fault Se
El vaso se cayó. (The glass fell down.)
8. Se Impersonal
This is a type of passive voice. It is used to describe situations in general. Sometimes this kind of verb has a direct object and other times it doesn’t. If a direct object is used, it requires the personal a.
Se vive bien en Aspen. (One lives well in Aspen.)
Se detuvo a los ladrones. (They stopped the robbers.)
9. Passive Se
This is the true passive voice.
Se dice coche en España y carro en México.
Se certainly is a multi-tasking word!