Yes. Monopotassium phosphate is also called potassium dihydrogen phosphate (KDP) or monobasic potassium phosphate (MKP). Dihydrogen phosphate is H2PO4-, so it is a monopotassium salt.
It is not a good proposal for making a buffer pH=5, and here it's why: Acid / base mixtures act best as buffers if their pH differs not more than 1.5 unit (up&down) from the pKa value of the acid...