ClearAll["Global`*"]

f[n_, l_, 
          r] = (Sqrt[((((2/n)))^3) (((n - l - 1)!)/(2 n (n + l)!))]) 
          LaguerreL[n - l - 1, 
            2 l  + 
              1, ((2 r)/n)] (((((2 r)/n)))^l) (E^(-r/n));

Integrate[f[4, 3, r]^2 (r^2), {r, 0, ∞}]

Plot[Evaluate[f[1, 0, r]], {r, 0, 10}, 
      PlotRange -> All]

Plot[Evaluate[{f[2, 1, r], f[2, 0, r]}], {r, 0, 15}, 
      PlotRange -> All]

Plot[Evaluate[{f[3, 2, r], f[3, 1, r], f[3, 0, r]}], {r, 0, 25}, 
      PlotRange -> All]