Breakdown of Aprender español lleva tiempo, pero me gusta practicar cada día.
Questions & Answers about Aprender español lleva tiempo, pero me gusta practicar cada día.
Because aprender is being used as an infinitive, and in Spanish an infinitive can act like a noun.
So Aprender español lleva tiempo literally works like Learning Spanish takes time.
If you said Aprendo español, that would mean I learn Spanish or I am learning Spanish, which is a complete statement, not the subject of the sentence.
Also, because the whole idea aprender español is treated as one singular subject, the verb is singular: lleva.