Elektronski računski centar - "electronic calculation center" i.e. a data processing center. Back in the 60s to some time into 90s, that's where the big iron computer would be, and the staff for it. All the data processing was done there, and printing of the reports.
First, the whole idea of data processing... is preposterous nowadays. Whatever is in the tables, is available online at once, shouldn't it be? But no, back then they didn't have validation on entry, various keys couldn't be checked against lookups at once but had to be manually picked from printed lists, actually the data entry went mostly blindly, and once one batch of entry was done, it was sent to the mainframe (on punch cards, punch tapes, magnetic tapes, cassettes, whatever you had at the time), and then verified against typical errors - wrong keys, impossible dates, impossible amounts etc, and would then print the erros report, and return the recording for rectification. Then the rectified records would be admitted to disk - either appended to some main table, or just left loose in the directory with the rest of the batches for the period. Then reports would be run on them, mostly just totals. Which was already a big thing, this totalling, even using a calculator, meant retyping most of the numbers and assuming there wouldn't be errors. Even bigger for longer period reports, and also for selective reports - one item, one customer etc, which would have meant either writing the same thing in two or three places, or scouring the paperwork to pick what belonged to that one. But on disk, this meant pulling data from several tables (which could mean dozens of loose files) to get one report - still faster, but that work was called processing. Nowadays, disks are big enough and machines fast enough and, besides, there are no loose tables, it's relational databases, so the so-called processing is done right away, and any resulting report can be done immediately. Still, in some places they prefer to have an intermediate phase - accounting above all, they want to check and recheck everything before committing ot to production database.
The data entry was done in different ways. In some cases, some kinds of dumb terminals would exist and even that was mostly concentrated in a couple of offices, which were then wired to the big box (in case of stour, the lines were up to 1km, in a 200mA loop), or had data recorded to cassettes (in case of kombinat) which were then taken to the ERC to be copied to the big iron, and then processed, reports printed, paper carried back with formatted cassettes.
In some older setups, there'd be an ERC without their own computer, but would rather own a timeshare in a bigger one. They'd enter data on Hollerith cards, and carry them in attache cases, process them, bring back the reports.
With the advent of PCs, the ERCs mostly ceased to exist, except in big enterprises, but the PCs were mostly concentrated in the offices of accounting and payroll. In DBA we started introducing computers in previously unlikely places, like the loading ramps, storage, production line.