writing ability; writing skill
Refers to the skill of composing clear, effective, or persuasive written text, often in an academic, professional, or creative context.
To improve your writing ability, it's important to read a lot and write a lot.
He has good writing skills, so he's entrusted with writing reports.
文才 refers more to literary talent or a natural gift for writing, whereas 文章力 is a broader term for practical writing skill.
Compound of 文章 (writing, composition) and 力 (power, ability). The exact historical derivation is uncertain, but the word is a straightforward modern formation.