This is a CAVAQUINHO (pronounced 'kavakiniu'). Although the back sides and neck are varnished the solid front is not and appears to untreated in any way. It has steel strings and is most commonly tuned D-G-B-D although the ancient Portuguses tuning is D-A-B-E but other tunings are also used.
Aparently in the late 19th century the Portuguese took this instrument to Hawaii and from this the ukelele was born.
Growing old is mandatory; growing up is optional. We don't stop playing because we grow old; we grow old because we stop playing. Do, or do not. There is no try.