\(y\) has units of m, \(v_0\) has units of m/s, \(t\) has units of s, and \(a\) has units of m/s^2. The constant 1/2 does not have units.
Hence, the first term on the right has units of: m/s s = m
While the second term on the right has units of: m/s^2 s * s = m
Thus, the equation is dimensionally correct.