肉にく付づきの良よい

also: にくづきのいい

Meanings

1

expression, i-adjective (yoi/ii class)

plump; well-fleshed; stout

Describes a person or animal with a solid, fleshy build; often positive or neutral, implying healthy plumpness rather than obesity.

付づ

き

が

良よ

く

て

元げん

気き

そう

だ

。

This dog is well-fleshed and looks healthy.

太ふとった
太った simply means 'fat' and can be negative; 肉付きの良い focuses on a solid, fleshy build without necessarily implying excess fat.
がっしりした
がっしりした emphasizes a sturdy, muscular frame; 肉付きの良い highlights fleshiness and plumpness.

Compound of 肉付き (fleshiness, body build) + の (attributive particle) + 良い/いい (good). The phrase literally means 'good in flesh attachment'.