What does 5guc mean on my Android phone?

It means 5g Ultra capacity which means it’s a faster version of 5g.

5g UC meaning 5G UC refers to customers that are connected to a type of 5G network , which is only shown on iPhones or Android phones with 5G support with smartphones, like iPhones 12 and13. This new network will appear if you are a T-Mobile customer and see a new “5G UC” icon in your iPhone status bar.31 Ara 2021

The 5G UC icon refers to T-Mobile’s “Ultra Capacity” 5G network , which indicates that users are connected to either mid-band or millimeter wave (mmWave) 5G. It is more likely to be mid-band with T-Mobile as this makes up the bulk of the carrier’s faster 5G network.30 Oca 2022