This is the 1311th most frequent Dutch word.
lekkere
Tasty or delicious.
Here, 'lekkere' is used as an adjective to describe the apple pie ('appeltaart'), referring to its tastiness.
Ik hou van de lekkere appeltaart.
I love the tasty apple pie.
In this sentence, 'lekkere' modifies 'kop thee' (cup of tea), emphasizing its pleasantness or quality.
Na een lange wandeling geniet ik van een lekkere kop thee.
After a long walk, I enjoy a nice cup of tea.
Here, 'lekker' is used directly as an adjective (not declined), describing ice cream ('ijsje') in general as enjoyable.