One of the easier conjugation forms to learn, the conditional tense for the most part simply adds ~ía, ~ías, ~íamos, ~íasis, and ~ían to the infinitive of the verb.

For example, hablar becomes hablaría and comer becomes comería.

The conditional tense is used in situations similar to when you use would in English to refer to potential events.

Yo hablaría, si ella me pregunta.
I would talk, if she asked.

Él lo comería, porque come todo.
He would eat it, because he eats everything.

Be careful to note however, that the "would" in these examples is referring to potential events. The equivalent to using "would" as a habitual past event - as in "he would go after school everyday" - is the imperfect tense.

Also, more properly, the conditional is a mood, not really a tense. This is because it makes no claim to when an action is being performed. For the sake of simplicity however, we call it a tense here.