So from this relation we see that the greater the ka value is, the smaller the PKA is. And likewise the smaller the K is, the greater the PKA is. So we see that the greater the Ka is, the smaller the PKA is. And the better that acid is, the more likely that it will donate that H plus ion. And likewise the smaller our Ka is, the larger the PKA is and the less likely our acid will actually donate that H plus ion. So a smaller PKA means the acid is strong and it will be very likely to donate that H plus ion.