ljudina

1. colloq. a great guy; a decent man
   Tvoj otac je prava ljudina. — Your father is a really great guy.
   Pomogao mi je bez pitanja, ljudina je. — He helped me without asking — he's a real gem.
2. colloq. a big man; a hulk of a man
   Na vratima je stajala ljudina od dva metra. — A two-metre hulk of a man was standing at the door.

It refers to a man but declines like nouns in -a; attributes and the predicate usually agree in the feminine (prava ljudina, s tom ljudinom, ljudina je ušla).