As you can see the 250 is fixed. It gets added to the cost no matter how many hours the lawyer works. This is most likely a flat fee. Just to meet the lawyer you pay $250.
The 200 gets multiplied by the hours worked. So the 200 is an hourly rate. The more hours the lawyer works, the more he gets paid because this part of the expression depends on the hours worked.
Thus, an interpretation of the expression 200h + 250 is that the lawyer charges a fee of $250 per consultation and an additional $200 per hour on top of that.
Logarithm is a function of mathematics which is used to calculate inverse function of exponents. The asymptotically smallest function will be the one that has smallest or no exponents. The exponent function is calculated in reverse when log is applied. The function with highest exponents will be largest asymptotically.