Adversative conjunctions Express opposition, contradiction, or contrast. They are sin embargo, aunque, mas, pero, sino, siquiera, etc.

Let's look at some example sentences.

El niño se resbaló en el lodo, sin embargo, no está sucio.
The boy fell into the mud, however, he is not dirty.

Es maestro, aunque le hubiera gustado ser médico.
He is a doctor, eventhough he would have liked to be a doctor.

María quería que nosotros trajéramos las maletas pero no pudimos.
María wanted us to bring the suitcases, but we couldn't.

Las muchachas no son extranjeras sino estudiantes.
The girls are not foreigners but students.

Te fuiste tan de prisa que ni siquiera tuve tiempo de hablarte.
You left in such a hurry that I didn't even got time to talk to you.

No obstante, si trabajamos más y hablamos menos vamos a lograrlo.
Nevertheless, if we work more and talk less we will make it.