Refers to the act of relaxing and enjoying the warmth of the sun. Often used in a leisurely, pleasant context. Cross-referenced with 日向ぼっこ, which is a more common variant.
See also: 日向ぼっこ
The cat is basking in the sun on the veranda.
On a winter day, basking in the sun feels great.
Compound of 日向 (ひなた, 'sunny place') and ぼこ, which is likely a euphonic change from ぼっこ, itself a nominalized form of the verb ぼっこする (to bask). The exact derivation of ぼっこ is uncertain.