Everything that Emily said above is true. I'll emphasize that an acoustic piano responds to the pianist so much more than a digital piano (next best) or keyboard (third choice). It becomes an extension of the pianist's fingers, wrists, forearms, upper body, emotions and effort. There's nothing comparable!
And I'll add that there are some nice used pianos being sold very reasonably. Your piano teacher can guide you in this venture and will possibly suggest getting a tuner/technician's advice as well.
Yes, an acoustic piano needs to be tuned and they are heavy to move. If you buy a digital or keyboard, I guarantee that you'll be disappointed because of its shortcomings. The only exception would be if you're intending to play in a band and then the type of music you'd be playing lends itself to less beauty as a solo instrument and more toward beat and volume.