This is the 4998th most frequent Arabic word.
اللي
"اللي" means "the one who" or "that" (used as a relative pronoun).
In this sentence, 'اللي' connects 'الأشياء' (the things) with the specification 'أحبها' (that I love). It acts as a relative pronoun introducing a defining relative clause.
الأشياء اللي أحبها تشمل القراءة والرسم.
The things that I love include reading and drawing.
Here, 'اللي' is used to refer to 'الشخص' (the person) and introduces the clause 'قابلته أمس' (whom I met yesterday), specifying the identity of the person.
الشخص اللي قابلته أمس كان لطيفًا جدًا.
The person whom I met yesterday was very kind.
In this example, 'اللي' connects 'السيارة' (the car) with the clause 'كنت أتحدث عنها' (I was talking about it) to define which car is being referred to.