THE FUTURE
The future breaks the pattern you have learned so far, in a way that makes it easier. Instead of removing the infinitive ending to find a stem, you keep the whole infinitive and attach the endings to it: hablar becomes hablaré, comer becomes comeré, vivir becomes viviré. One set of endings serves every verb in the language.
One set of endings, on the whole infinitive
There is no -ar/-er/-ir split. The classes only differ in their infinitives, and the infinitive is kept. Every form carries a written accent except nosotros.
hablar, comer, vivir + …
When Spanish actually uses it
Everyday speech often prefers ir a + infinitive for plans (voy a hablar, “I'm going to speak”), or even the plain present for the near future. The conjugated future leans more formal or more distant, and it has a second job English handles differently: guessing. Used about the present moment, it expresses probability.
Mañana hablaré con el director.
Tomorrow I will speak with the director. A firm statement about the future.
Serán las diez, más o menos.
It must be about ten o'clock. The future of probability: a guess about right now, not a prediction.
The twelve irregular stems
Twelve verbs and their compounds swap the infinitive for a shortened stem. The endings never change, even here. The stems come in three flavours:
the vowel drops
saber, poder → podré, querer → querré, caber
a d slips in
tener, poner → pondré, venir → vendré, salir → saldré, valer
a short stem
decir; hacer → haré (and haber → habré)
Compounds inherit their base verb's stem: contener gives contendré, componer gives compondré. See tener or decir with every irregular form marked in this color.
Learn the stem once, get two tenses
The conditional (hablaría, “I would speak”) is built on exactly the same stem as the future, regular or irregular: tendré and tendría, diré and diría. Master these twelve stems and you have already done the hard part of a tense you have not met yet.