Learn Romanian: Pe măsură ce ne maturizăm, înțelegem viața mai bine.

Pe măsură ce specifically implies a gradual, proportional progression (literally "in the measure that"). You use it when one thing evolves in proportion to another, like maturing and understanding. If you just wanted to say two independent actions were happening at the exact same time without that proportional link, you would use în timp ce (while).

Does the verb following pe măsură ce always take the indicative mood, as seen with ne maturizăm?

Yes, it takes the indicative mood. Because pe măsură ce describes a factual, ongoing process in reality (the actual process of maturing), it triggers the indicative rather than the subjunctive.

Why is maturizăm reflexive here (ne maturizăm)?

In Romanian, many verbs that express a change of state, an ongoing transformation, or "becoming" something are reflexive. The verb is a se maturiza. Since the subject is "we", you must use the corresponding first-person plural reflexive pronoun ne.

Why does viața have a definite article here when the English translation just says "life"?

In Romanian, abstract concepts and nouns used in a broad, universal sense require the definite article. While English leaves the article out to say "life in general", Romanian requires you to say viața (literally "the life").