In French you form the conditional tense in 2 simple steps:
1) Take the future stem of the verb. E.g - manger
2) Add the imperfect endings. E.g - ais, ais, ait, ions, iez, aient.
You use the conditional tense to talk about what 'would' happen in the future.
Many verbs have irregular stems in the future and these must also be used in the conditional tense. Some examples are given below.
Aller: ir-
Avoir: aur-
Etre: ser-
Faire: fer-
Vouloir: voudr-
Example sentences: I would go to Spain. - J'irais en Espagne.
He would eat an apple. - Il mangerait une pomme.
We would do our homework. - Nous ferions nos devoirs.