What does roosevelt mean by ""speak softly and carry a big stick""?

Roosevelt means that one should use reasoned foresight in order to deal with domestic and foreign policy and act justly in every case, "speak softly," and have a strong military in order to make the adversary aware of the consequences of his possible misdemeanours.  

Explanation:

Roosevelt used this peculiar aphorism in order to showcase the importance of  peaceful negotiations, whilst having a strong army as backup in case something goes wrong. This bears strong resemblance with , pursuing political decisions based on particular circumstances. The aphorism I also alludes to a Machiavellian use of power when the circumstance demands. The politician should thus negotiate peacefully, according to the circumstance at hand, and intervene with military power, whenever the situation demands.

ok sorry the answer is a. by their religion

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.