Officially, N95, KN95, or KF94 masks are single-use: you should dispose of them after the period of exposure.
Nevertheless, for members of the general public—not if you are using your mask in a health-care setting—reusing masks a few times is okay as long as you follow some safety guidelines: https://www.smithsonianmag.com/smart-news/can-you-reuse-a-kn95-or-n95-mask-experts-say-yes-but-follow-these-steps-180979404/.
Always discard of your mask if it is damaged, shows signs of wear, or the straps fail.
