What the abbreviations actually stand for depends on who is entering the data. I'd imagine it's criminal history data from either DPS or a local jurisdiction. My best guess is that it is a charge for Possession of a Controlled Substance in a Drug Free Zone ("DRUG FREE ZON-CS"), with an amount of less than 1gram of a substance in Penalty Group 1 ("O/1G-PG1").
Penalty Group 1 under the Health and Safety Code (TX Health and Safety Sect. 481.102) includes several controlled substances, most notably opiates, opium derivatives (inc. heroin), and cocaine. Possession of a Penalty Group 1 Controlled Substance of an amount less than 1 gram is a State Jail Felony and carries from 6 months to 2 years in state jail or up to 5 years of probation (TX Health and Safety Sect. 481.112).
However, this charge appears to be enhanced by the Drug Free Zone provision ((TX Health and Safety Sect. 481.134) which enhances possession of a PG1 CS to a 3rd degree felony which carries from 2-10 years in prison or up to 10 years of probation. The State would have to allege and prove that the defendant had the CS in a prohibited zone (includes schools, playgrounds, youth center, higher education facility, and "video arcade facilities").
You haven't included any information about how the case was disposed of, so it could be an arrest, charge, acquittal, dismissal, or conviction.
In Texas, different jurisdictions use different codes in their computer systems to represent various crimes. What you have is just an abbreviation used in that jurisdiction for an offense. I'm not as familiar with that abbreviation as I am with the ones in my home county (Bexar County), but I can guess that it is for Possession of a Controlled Substance, Less Than 1 Gram, in a Drug Free Zone. PG1 probably means "Penalty Group 1," which includes heroin, meth, and cocaine. So, this probably means that somebody is charged with possessing less than a gram of some drug in penalty group 1 (not weed) in a place designated a "drug free zone," like a school. This is a felony.
Possession of a controlled substance