Hi - our paths cross again!
I have replied on similar questions many times, so if you 'Search' on my name and Piano, Keyboard, Music, etc you will find my earlier replies.
I am pleased to hear he is getting interested in music now; remind me how old he is, or what Year group he is in? And am I correct in thinking you are not in UK?
For a beginner, an electronic Piano or even a Keyboard, is OK to START to learn the basics. As students progress to more advanced music, an electronic Piano with 76 keys is recommended, but the need for that may be a few years away:
www.yamahamusiclondon.com/NPV80-Piaggero-Digital-Keyboard/pidYAM-NPV80
With an adult helping, and also use of on-line tuition, a teacher is not ESSENTIAL to start with, as there are many books that a student can use to start learning.
'PIANO' and 'KEYBOARD' involve two different methods and styles of playing, and for a beginner I suggest Keyboard is easier to start with, and is more fun. HOWEVER, some people want to play only Classical Music, in which case Piano would be necessary.
Look up my earlier replies, then we can 'talk' again in a few days.