Coordinating Conjunctions

pero	but
o	or
y	and
entonces	so, thus
ni … ni	neither … nor
pues	then

Coordinating conjunctions link words, phrases or independent sentences.

These conjunctions combine forms of the same grammatical category (adjective + adjective, noun + noun, clause + clause, etc.) so they can be used to link adjectives, nouns or verbs within a sentence.

Ha sido un cambio muy radical, pero un cambio que siempre voy a agradecer.
It has been a radical change but a change that I always am going to be grateful for.

In addition, o, y, ni, pero, entonces, and pues are also used to combine two clauses into one:

Tengo una compañera de trabajo, ella es maestra y me duele decirlo, pero es una persona que a veces en lugar de corregirte se hace burla.
I have a collegue, she is a teacher and it hurts me to say it but she is a person that sometimes instead of correcting you she makes fun.

O, pues, entonces, y pero can link two separate sentences. They are usually placed at the very beginning of the second sentence.

Lo tuve que hacer aquí. Pero, algo que mi madre me decía “hija, todo trabajo es honroso, todo trabajo es honroso”.
I had to do it here. But something that my mom told me “my daughter, all work is honorable, all work is honorable”.