The sentence means:
If you save or earn 1 cent every day, and you keep doing it for 365 days (a full year), the total will be $3.65.
Why?
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1 cent = $0.01
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365 days × $0.01 = $3.65
So the idea is simply showing how small amounts add up over time. 
People often use this example to explain consistency: even tiny daily actions can grow into something bigger over time.
