Numbers can be positive, negative or zero. Zero is neither positive nor negative. Positive numbers are the ones you most encounter in everyday life, such as 34, 9.22, etc. When shown on a number line, they are the ones usually drawn on the right of zero, getting larger as you move to the right
Positive numbers usually have no sign in front of them. So a number like 67 is taken to mean a positive number. In case of doubt however, a '+' sign can be placed in front to firmly distinguish it from a negative number. Example +65, +0.2.
A positive number such as 6 can be spoken as 'six' , 'positive six' or sometimes 'plus six', although 'plus' is usually used to mean add.
One unfortunate thing in math is that the '+' symbol is used for two different things. It signifies a positive number, as described above, but it also means 'add' or 'plus'. For example 2+3 means 'two plus three' with a result of 5. Here, the plus-sign means addition. The same confusion happens with the minus ( – ) sign. See Negative numbers.
See also Doing arithmetic with positive and negative numbers.
Strictly speaking, 'plus' means addition. This is a completely different idea to 'positive'.
Sometimes, when talking about a positive number such as +4, people will say 'plus four'. This in not correct. Train yourself to say 'positive four' instead.