It is simply a collection or set with operators defined on them. Nothing more, nothing less.
If the structure, with one operator, satisfies the requirements of closure, associativity, identity and invertibility in respect of that one operator, then it is a Group.
A second operator and additional qualities need to be met for it to be a Ring and further conditions are required for a Field.
If you wish to explore the basics, you can look at Group, Ring or Field in Wikipedia but make sure you also put mathematics in your search engine!
It is usually called a set.
expression
A mathematical statement that contains an equal sign is called an equation.
A mathematical sentence that contains an equal sign is called an equation
An equation or inequality that expresses a resource restriction in a mathematical model is called
vinculum
If you mean the symbols like +, -, etc., those are called "operators".If you mean the symbols like +, -, etc., those are called "operators".If you mean the symbols like +, -, etc., those are called "operators".If you mean the symbols like +, -, etc., those are called "operators".
Set
It is usually called a set.
expression
its called an expression
It is usually called a set.
A mathematical phrase containing numbers and operations is called an expression. Expressions can be joined together with an equals sign to form an equation.
A solution set makes a mathematical sentence TRUE.
It is called cell
numbers
An expression.