What is the meaning of Play_along?

Used other than figuratively or idiomatically: see play, along.

To take part in a charade, deception, or practical joke.

To participate in a joke or trick while hiding one's knowledge of its true nature.

To play a musical instrument in synchrony with a playback of a recording.

To cooperate or go along with a plan.

To pretend to cooperate or go along with a plan.

To manipulate (someone).

Source: wiktionary.org