1.
slim; slender (of body shape)
Describes a person who is attractively thin. Generally a positive word, unlike 痩せている which can be neutral or negative.
2.
slim; compact; streamlined (of objects or systems)
Describes products, designs, or organizational structures that are compact, efficient, or reduced in size.
A loanword from English. Functions as a na-adjective (スリムな + noun) in Japanese. Always carries a positive nuance — "slim" in an attractive or efficient sense, never "skinny" in a negative way.