How much protein you should have in your diet depends on a variety of factors: your lifestyle, age, muscle mass, how much exercise you do and what your fitness goals are. If you train regularly you should be aiming for 1-2g of protein per kg of body weight.
As an example, 1.6g per kg is an average amount of protein and we’ll use an average man who weighs 75kg. So:
75(kg) x 1.6(g/kg) = 120 grams of protein a day
This is, of course, just a guide, and protein comes from a variety of sources. Nothing is 100% protein, an average chicken breast will give you around 25-30g of protein per 100g. If you’re following a vegan diet, you may find eating enough protein slightly harder than someone who is a meat eater, or even pescatarian/vegetarian.