What does PRSC-T3R mean on my security data section on my SRB?

T3 is short for Tier 3 investigation and the R stands for reinvestigation. The tier system replaced what had previously identified by the investigation completed and Tier 3 level investigations had.gone by several names through the years. Most recently NACLC if I remember correctly. A favorable T3 makes you eligible for a secret clearance if you require a secret clearance. It is also necessary for some other positions of trust not necessarily involving classified information.

A T3R is a PR for a Secret clearance. I'm not sure what PRSC means - maybe that it's a PR?

T3 is what used to be NACLC (Secret)
T5 is what used to be SSBI (TS)

You need to go talk to your S2 to check your JPAS/DISS to see if you have an open T5. Then once you have an open T5, your S2 should be sending an interim SCI request to the SSO.

Again never trust the data on the security clearance section on the SRB - it's not always accurate.