。
I love you.
Literal
Loving.
The casual contraction of 愛している, with the い of ~ている dropped. Worth noting that Japanese uses ~ている for 'love' because 愛する describes a state, not an instantaneous event — the ongoing-state interpretation of ~ている. Also note: 愛してる is a relatively strong, Western-influenced expression; many Japanese speakers prefer 好きだ or 大好きだ in actual romantic contexts.