Inside any loop, break leaves the loop at once and continue skips the rest of the current pass. A loop can also end with an else block, which runs only if the loop finished without a break.

for n in [4, 9, 15, 21]:
    if n % 2 == 0:
        continue          # skip evens
    if n > 10:
        print("stopped at", n)
        break
    print("odd", n)
else:
    print("not printed: break ran")

When the exit test belongs in the middle of the loop, write while True and leave with break:

total = 0
while True:
    total += 7
    if total > 30:
        break
print(total)  # 35

Read else on a loop as "no break happened". It fits searches: break when you find what you want, and put the not-found case in else. Keep loops short, so every break is easy to spot.

Write total_until_stop(numbers) that adds the numbers in order, skips negative ones, and stops at the first 0. Write smallest_divisor(n) for n of at least 2, returning the smallest divisor above 1 (which is n itself for a prime), trying d only while d * d <= n.

The explanation opens here once every check passes.