Emission of a positron results in the conversion of a proton into neutron, along with the release of neutrino. Thus, the number of protons decreases and of neutron increases, i.e., $n / p$ ratio increases and the nuclei becomes stable.
$\underset{\text{Proton}}{{ }_{1}^{1} H} \longrightarrow \underset{\text{Neutron }}{{ }_{0}^{1} n}+ \underset{\text{Positron}}{{ }_{+1} e^{0}}+v$