DL338 serves multiple routes, but the most common is between Kailua-Kona, HI (KOA-Kona Intl.) and Los Angeles, CA (LAX-Los Angeles Intl.). If on a non-stop flight, you'll step off the plane in around 5 hours and 10 minutes. Multi-stop flights can also operate under the same number, as can services on other routes.
DL338 is a flight number that serves a number of different routes. If you're heading off on the most popular route, Kailua-Kona, HI (KOA-Kona Intl.) to Los Angeles, CA (LAX-Los Angeles Intl.), you're likely to be boarding a Boeing 757-200.