Everything you've said in Spanish so far has been about facts — things that happen, happened or will happen. Those verbs are in the indicative: Hablas español. — You speak Spanish.

The subjunctive (el subjuntivo) is for things that aren't facts yet: what someone wants, hopes or asks for. Espero que hables con él. — I hope you talk to him.

It nearly always comes after que, in the second half of a sentence; the first half switches it on. To build it, take the yo form of the present, drop the -o and swap the vowel: -ar verbs take -e, -er and -ir verbs take -a.

Pronoun	Hablar (yo hablo)	Comer (yo como)	Vivir (yo vivo)
que yo	hable	coma	viva
que tú	hables	comas	vivas
que él / ella / usted	hable	coma	viva
que nosotros	hablemos	comamos	vivamos
que vosotros	habléis	comáis	viváis
que ellos / ellas / ustedes	hablen	coman	vivan

In the subjunctive, yo and él / ella share one form: que yo hable, que ella hable. Now try escuchar (yo escucho) — the forms you'd use after que.