The equation means the quantity on the left of equals sign is equal in value to the quantity on the right of the equals sign.
So examples of equations are 2+1=3; 7+5=2×6; 1+2+3-4=2, 24➗6=2+2.
But some equations may contain letters, where a letter represents a value which needs to be found:
x+1=3, for example, means that x=2 because the quantity x+1 has to be equal to 3. This is called solving the equation, because the equation tells you that the quantity on the left MUST be equal to that on the right. You can add, subtract, multiply or divide by equal quantities on each side of the equation and the equation still holds true.
So, because 2+1=3, 14+7=21 (both sides multiplied by 7); 2+1+17=3+17; 5(2+1)=5×3, (2+1)/6=3/6; etc.