If you know what is an equation, then understanding differential equations are simple.
In an equation there are 2 expressions separated by an equal sign. for ex 2x = x +7
And the goal of the equation is to solve for the unknown(s), for the case mentioned above the unknown is variable 'x'
So the differential equation is an equation where we have to find unknown y whose derivative is provided to us.
for example:
d(y)/dx = 10
But here in this case y is not just a number instead it is a function whose derivative is y'.
the solution of the above equation is a function:
y = 10x + C, where C is an arbitrary constant.