The word "balance" comes from Latin roots via Old French.  It originates from Latin bilanx ("two-scaled") combining bi- ("twice") and lanx ("dish, plate, or scale pan"), describing the two pans of a weighing scale.  It was borrowed from the Old French balance and entered English in the 13th century as balaunce, meaning scales or equilibrium.  Its core idea of two equal parts or weights evolved from weighing instruments to abstract concepts like harmony and accounting. 

According to the Oxford English Dictionary (OED), the noun form of "balance" appeared in English around the late 13th century (e.g., 1297), while the verb "balance" was first recorded later, in the late 1500s (specifically 1583), borrowed from French and used by Philip Stubbes. 

Balance in writing means using parallel structures, contrasting ideas (antithesis), and rhythmic sentence variety for clarity and impact, seen in examples like "It was the best of times, it was the worst of times"  (contrast) or "She like reading, writing, and painting" (parallelism), balancing description with dialogue, or balancing story elements like conflict and character development. It creates memorable, pleasing, and believable prose by matching grammatical structure or contrasting opposing ideas.  

Just the facts:

BALANCE Definition & Meaning - Merriam-Webster

BALANCE Synonyms: 183 Similar and Opposite Words | Merriam-Webster Thesaurus

Balance | Definition of Balance by Webster's Online Dictionary