have a fix on (something)

To have a firm, clear understanding or determination of something. I hope everyone has a fix on the material, as you'll be tested on it next week. I thought I had a pretty good fix on English idioms, but I don't understand this one at all!

Common Names:

Name	Pronounced	Usage
Abdullah	‘ahb-DAH:L-lah (Arabic), ‘ahb-DOOL-lah (Arabic), ahb-dool-LAH (Turkish)	Arabic, Turkish, Malay, Indonesian
Eduard	E-doo-ahrt (German)	German, Russian, Czech, Slovak, Croatian, Catalan, Dutch, Estonian, Romanian, Georgian, Armenian
Ondrej	-	Slovak
Ebenezer	eb-ə-NEE-zər (English)	Biblical
Metod	-	Slovene, Slovak
Joshua	['dʒɔʃwə]