Terminology

Bug

No, not an insect. A bug is basically something in a program that's not working as it should. Often leads to a bug report and bug fixing.

Locale

That's your language, plus a bit of extra info. Not all languages are locales and vice versa. For example, French is one language but it usually comes marked as fr-CA and fr-FR. That's because something that applies in Canada (CA) might not apply in France (FR). The currency for example, so if you're software is aiming at Canada, you want CA$, not €.

Chinese usually comes as two locales but covering just the one language. Usually you'll get zh-TW and zh-HANS (or something like that). Both are for the language Mandarin but essentially (currency and suchlike aside) they cover the differences in the writing system: the long character forms used in Taiwan and Hong Kong (e.g. 中國) and the abbreviated forms (e.g. 中国) used in Mainland China. But both are pronounced zhōngguó.

Then there's other stuff that is linked to your language and country, things like the date formats (month before day or day before month), what separates digits (1,000 or 1.000), whether to use 24 hour clock or AM/PM and so on. It can get quite elaborate but you don't have to compose War and Peace, most are quite simple.

So, in software terms, your language will usually be referred to as a locale.

Localization

Often abbreviated l10n (don't ask why), the first letter being an L. To you and me, translation. A new word was coined because when you translate software, it's not just translation. Other things get involved, like setting the right codes which tell the software what language its in, picking search engines which are right for your language, changes number settings (for example, does your language use a comma or dot as a separator between thousands: 1,000 or 1.000?). Stuff like that.