Interpret the root of an independent variable

Hello everybody,

I have a regression model of the following form to investigate: y =b_0 + b_1 * x_1 + b_2 * sqrt(x_2)

Now I want to give an interpretation of the model and I do not know how to interpret the influence of x_2 respectively b_2.

The formulation for x_1 would be: An additional unit x1 increases y by b_1 units.

But how would the case be interpreted at x_2?

Thank you in advance!