Final answer:
The Polish inmate advises the other inmates to remain silent and not fall for the police officer's speech in the prisoner's dilemma scenario. By staying quiet, they can potentially get a shorter sentence.
Step-by-step explanation:
The advice that the Polish inmate gives to the other inmates is to ignore the police officer's speech and remain silent. In the given scenario, the police officer is using a tactic called the prisoner's dilemma to try and get the prisoners to confess. However, if both prisoners remain silent, the evidence against them is not strong, and they will end up with only two years in jail each. By staying quiet, both prisoners can get a shorter sentence than if they were to confess.