The strength rating gives a quick yes/no answer, but the entropy score is more informative. Two passwords can both be rated Good but have different entropy values — the one with higher entropy is objectively stronger. Focus on reaching the entropy threshold for your account type: 60+ bits for general, 80+ for important, 100+ for critical.
The crack time estimate assumes the attacker is using modern GPU hardware (billions of guesses per second). If your password shows centuries to crack, it is safe against offline attacks. If it shows hours or days, consider adding length and character variety.
Use the improvement tips as a checklist. Each tip you address adds meaningful strength. The most impactful change is always adding length — going from 12 to 16 characters adds roughly 20 bits of entropy.