Spectral count reflects relative abundance of a protein by counting how many times all peptides of a proteins have been fractioned. The Spectral Count algorithm can be run for a given context ; it will loop on every protein groups of this context.
Several other characteristics may be useful to collect.

1. Select the context of your choice (for which protein grouping have been executed)
2. Right-click and select Algorithms > Compute Spectral Count
3. Spectral count results are available in Protein Group properties