に限（かぎ）る is a combination of the 格助詞（かくじょし） (case marking particle)
に (marking a location), and the う - Verb 限（かぎ）る ‘to limit’. This expression can be translated as ‘there’s nothing better than (A)’, or ‘there’s nothing like (A)'.
に限（かぎ）る may be paired with verbs in their base form, or with nouns.
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暑（あつ）い日（ひ）は冷（つめ）たいシャワーを浴（あ）びるに限（かぎ）る。
There is nothing better than taking a cold shower on a hot day.
回転（かいてん）寿司（すし）はくら寿司（ずし）に限（かぎ）る。
There is nothing better than Kurazushi when it comes to kaiten-sushi.
に限（かぎ）る may also appear with verbs that have been negated with the 助動詞（じょどうし） (auxiliary verb) ない. Care will need to be taken with translating these sentences, as they will express that ‘there is nothing better than -not- doing (A)'.
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寒（さむ）い日（ひ）には温（あたた）かい部屋（へや）を出（で）ないに限（かぎ）る。
There is nothing better to do than not leaving your warm room on a cold day.
休（やす）みの日（ひ）には仕事（しごと）をしないに限（かぎ）る。
There is nothing better than doing no work on a day off.
The literal meaning of 限（かぎ）る is 境（さかい）
を付（つ）ける ‘to set a boundary’. This means that
に marks the location (or situation), within which the speaker then states as being ‘the boundary’. Because of this, ‘to be bound to’, or ‘to be limited to’, are also possible translations of に限（かぎ）る.
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暑（あつ）い日（ひ）にはアイスクリームを食（た）べるに限（かぎ）る。
I am bound to eat ice cream on a hot day.
この施設（しせつ）を利用（りよう）できるのはこのアパートの住民（じゅうみん）に限（かぎ）る。
Using this facility is limited to those who live in this apartment complex.