Cuando termine el semestre, quiero cortarme el pelo.

When the semester ends, I want to get my hair cut.

Breakdown of Cuando termine el semestre, quiero cortarme el pelo.

• yo: I
• querer: to want
• cuando: when
• el semestre: the semester

Questions & Answers about Cuando termine el semestre, quiero cortarme el pelo.

Why is it termine and not termina or terminará?

Because after cuando referring to a future event, Spanish normally uses the present subjunctive.

So:

• Cuando termine el semestre... = When the semester ends / when the semester is over...

Even though this is about the future, Spanish does not usually say cuando termina here.

Compare:

• Cuando termina el semestre, siempre estoy cansado.
  = When the semester ends, I’m always tired.
  This is a habitual/repeated situation, so indicative is used.

• Cuando termine el semestre, quiero cortarme el pelo.
  = a specific future situation, so subjunctive is used.

Why is it quiero if the haircut will happen in the future?

Because quiero describes your present desire or intention.

The sentence means something like:

• Right now, I want to get my hair cut when the semester ends.

Spanish often uses the present tense this way:

• Quiero hacerlo mañana. = I want to do it tomorrow.
• Espero verte la semana que viene. = I hope to see you next week.

So the wanting is now, even if the action happens later.