Hello
bit rate is related to banwicth by the channel capacity equation, this is
C = B log2(1 + S/N)
where C is the channel capacity in bits per second, B is the bandwidth and S/ N is the signal to noise raion.
Now, bit rate is related to symbol rate by the bit to symbol mapping, it depends on the modulation you are using, you can modulate 1, 2 , 3, .. bit per one symbol
About the spectrum efficiency I have seen many definitions fo far, I will give the one I have at hand right now. Bandwidth efficiency is defined as the ratio of the bandwidth required to accept a given data rate divided by the data rate. (data rate is given by bits per second)
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Sal