Product Market Fit
In the most simplest of words it means finding your place in the market.
You can understand the market as a collection of requirements and demands. Constant stream of ever changing requirements/ demands/ problems faced by the market in general. Why market - just another word for a group of people in economic sense. People with the willingness to buy.
Product - Any offering is a product.
As a an employee - You are the product with your existing skillset. Your employer or the industry is the market.
As a business - your product/ service is the product. Your customers/ people willing to buy are the market.
As a human looking for a relationship - you're the product with your emotional maturity and ability to connect. The kind of partner that you're looking for is the market.
And in each of these situations you will not be able to find the success that you're looking for - If you do not arrive at the product market fit.
It goes back again to your ability to Solve and Sell. And how well do you deliver on your promises to the market.
Market is always optimising to meet its demands.