LUT is an acronym for “Look Up Table” – these are used frequently in color grading. These are files you can load in to your editor and apply to your footage to achieve certain looks to your footage – commonly these emulate various film stocks.
Links:
Some free LUTS to start with
https://www.groundcontrolcolor.com/free-luts.html
http://juanmelara.com.au/print-film-emulation-luts-for-download/
ImpulZ Luts from Ground Control
http://www.colorgradingcentral.com/impulz/
DaVinci Resolve from BlackMagic Design
https://www.blackmagicdesign.com/products/davinciresolve