What is batch brew coffee?

batch
noun: batch; plural noun: batches
1.
a quantity or consignment of goods produced at one time.
"a batch of cookies"
informal
a number of things or people regarded as a group or set.
"a batch of hostile letters came"
synonyms: group, quantity, lot, bunch, mass, cluster, raft, set, collection, bundle
consignment, shipment
"when can we expect the next batch of invoices?"
Computing
a group of records processed as a single unit, usually without input from a user.

verb
verb: batch; 3rd person present: batches; past tense: batched; past participle: batched; gerund or present participle: batching
1.
arrange (things) in sets or groups.
google.com

"Batch" is a term in chemical or other processing meaning you put all the ingredients into a pot and produce a quantity of product. The alternative is continuous process where the ingredients are mixed in proportion as the stream keeps moving.