How can I understand Equations better?

Step 1
Definition:
In algebra, an equation can be defined as a mathematical statement consisting of an equal sign between two algebraic expressions.
Step 2
Example:
${\displaystyle x+y=2}$ is an equation, in which ${\displaystyle x+y}$ and 2 are the two algebraic expressions separated by equal sign
Moreover,
In an algebraic equation, the left-hand side is equal to the right-hand side.
Consider,
An equation ${\displaystyle 2x-3y=21}$
${\displaystyle 2x-3y}$ expression is in the left-hand side, which equal to the expression 21 on right-hand side.
Step 3
Equations are divided in the parts given below:
Consider,
An equation ${\displaystyle 2x-3y=21}$
1] Terms: 2x, 3y, 21 are the terms in the equation consider above,
2] Variables: x , y are the two variables,
3] Operator: The operator is subtraction which "-",
4] Coefficients: A constant term with the variables are the coefficients of the equation here 2 and -3 are the two coefficients, ( sign of the coefficient matters the most)
5] Expression: ${\displaystyle 2x-3y}$ is the expression of the considered equation,
6] Left-hand side=Right-hand side
Without variables is also forms an equation:
Consider ${\displaystyle 1+1=2}$ is also an equation because it consists of equal sign.
Step 4
Example which is not an equation given below:
${\displaystyle 5x-y+1}$ is not an equation, by the definition of an equation consists a equal sign.
${\displaystyle 5x-y+1}$ is only an expression.