$C _6 H _5 CH _2$ electron donating group due to $+ I$ effect. So, It is able to Increase

the electron of $N$ of $- NH _2$ group. Thus, due to higher electron density, rate of donation of free pair of electron is increased i.e., basic character is higher. Phenyl and nitro groups are electron attractive group. So, they are able to decrease the electron density of $N$ of $NH _2$ group. Hence, they are less basic with aniline.