Answer
The IUPAC name of the compound is $cis-1-methyl-3-propylcyclobutane$
Work Step by Step
The compound has 4 carbon atoms in the carbon ring ($-but$). There is a $methyl$ group and a $propyl$ group attahced to the ring, both on the same side of the plane ($cis$). Numbering is done according to the alphabetical order of the substituents. So, the IUPAC name of the compound is $cis-1-methyl-3-propylcyclobutane$