Market Profiling arranges trading sessions into so-called 'profiles' instead of classical charts representations. This can be viewed as either:

1) TPO (Time Price Opportunity) - how much TIME, price has traded at different levels

2) VPO (Volume Price Opportunity) - how much VOLUME, price has traded at different levels

They are often used together, and share a few things in common:

1) 'Point of Control' - the price traded, with the most Time/Volume during that session

2) 'Value Area' - the price range traded within 1 standard deviation (or 68-70%) of TIME/VOLUME of that session

When paired with 'Auction Market Theory' or even 'Orderflow' (Level 2 data + DoM), market profiling can help identify favourable areas to trade, and NOT to trade.

There are some good books that go into detail:

1) 'Steidlmayer on Markets: Trading with Market Profile' by J. Peter Steidlmayer - arguably the genesis of the concept 

2) 'Volume Profile, TPO, Order Flow' by Johannes Forthmann - a more recent publication

3) FTMO one pager - if you want a quick overview to tide you over