"Descargar are gratis" is Spanish for downloads are free. The phrase is commonly used in reference to music, computer and phone application downloads.
Translator tools do not always provide exact translations from language to language, and the phrase "descargar are gratis" is a perfect example. While phrased correctly in Spanish, it's precise English translation is "download are free," which places the singular subject "download" with the plural verb "are." Differences of this nature are common when translating languages. While translator tools do not catch and correct these common linguistic differences, a human translator can detect the differences and make sense of the translated text.