Likely a shorthand for "Orkestr Bratya" (Orchestra of Brothers). This is a common naming convention for family-based brass bands or folk ensembles in Slavic regions.
Often a surname or a regional descriptor. In music contexts, individuals like Clair Babecki have been involved in music education and ensemble direction.
The string does not appear to correspond to a well-known academic subject, historical event, or published literary work. Instead, its structure—using underscores and a date—strongly suggests it is a specific digital file name or a local directory entry, likely associated with a 2019 live recording of a folk or brass ensemble from Eastern Europe (possibly Poland or the Balkans, given the terms "orkbratya" and "babecki").