Adding nicer fonts to your terminal vim is not as easy as one would think but here is a good path to follow to make it happen on a mac

brew tap caskroom/fonts
brew cask install font-hack-nerd-font

On your .vimrc

set encoding=utf8
let g:airline_powerline_fonts = 1

And then change it on iTerm2

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This has been shamelessly ripped off from here

Now look how beautiful it looks with airline!

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