Change hours to minutes.

$1$ hour $=60$ minutes

Use proportions to solve the problem. Assign the variable t to represent the unknown number of words.

$\frac{500\text{ words}}{60\text{ minutes}} = \frac{t\text{ words}}{10\text{ minutes}}$

You can simplify the left side of the proportion and make the denominator $10$ by dividing the numerator and denominator by $6$. The numerator will also be the answer.

$83.33$ words (about $83$ words)