What does 'churn out' mean?

[ab]

English Grammar Tests, Elementary Level

ESL/EFL Test #84 "ESL Prepositions", question 5

The factory churns ......... thousands of pairs of low cost shoes every day.

(a) out
(b) off
(c) in
(d) into

English Grammar Tests, Elementary Level

ESL/EFL Test #84 "ESL Prepositions", answer 5

The factory churns out thousands of pairs of low cost shoes every day.

Correct answer: (a) out

Your answer was: ?
_________________________

Hi,

what does "churn out" mean?
thanks

ab

[Vangelic1]

churn out is an expression that means: produces, makes, creates

It implies creating something quickly as if on an assembly line.