Connecting Adjectives with て-form:

In the sentence, the て-form of the adjective いい (good), which becomes よくて, is used to connect two adjectives describing the boy. This form is used when listing multiple adjectives in Japanese to describe something. The て-form effectively means "and" in this context, linking the characteristics of being smart and kind together to describe the 少年(しょうねん).

It's important to note that the て-form can also imply a temporal or logical sequence when used with verbs, but when used with adjectives as in this sentence, it serves to list qualities or states of being in a non-temporal sequence.

The word 元気(げんき)  in Japanese is very rich in meaning and cultural significance. It can mean "healthy," "energetic," "lively," or "in good spirits." It's a commonly used term to describe someone's well-being and is often heard in greetings such as お元気(げんき)ですか？ (How are you?).

Describing someone, especially an elderly person like an おばあさん (grandmother), as 元気(げんき) is a compliment implying that she is active, lively, and in good health, which is valued in Japanese culture where there is great respect for the elderly. The term reflects a holistic view of health, encompassing physical, emotional, and spiritual vitality.

The verb 食(た)べましょうか combines the volitional form of the verb 食(た)べる (to eat), which is 食(た)べましょう, with the question particle か.

The volitional form is used to suggest or propose an action, equivalent to "let's" in English.

When followed by か, it turns the suggestion into a polite invitation or offer, roughly translating to "Shall we...?" or "Should we...?". This construction is a common and polite way to invite someone to join in an activity without being too forceful, allowing the listener to agree or decline the suggestion comfortably.

The term かっこいい, which is colloquially used to express that someone or something is "cool," "good-looking," or "stylish," is interesting because it has a broad application in modern Japanese language.

It can be used to describe a person's appearance as well as their demeanor or even a particular object that is fashionable or impressive.

The word originates from 格好(かっこう) which means "appearance" or "shape," and いい which means "good." Over time, it became slanged to かっこいい. It is commonly used among all age groups and can apply to both males and females, despite originally being more masculine in connotation.