From Proto-Semitic *ʔarṣ́-. Compare Hebrew אֶרֶץ (érets), Aramaic אַרְעָא (ʾarʿā) / Aramaic ܐܪܥܐ (ʔarʕā). False cognate of Dutch aarde.
Practice speaking and memorizing "أرض" and many other words and sentences in Arabic.