One of the biggest challenges for learners of Japanese is dealing with what isn't stated in a sentence. My German-fluent sister once told me that the purpose of German grammar was to get the subject and the verb as far from each other as possible (to confuse people trying to learn the language, I guess). In Japanese, the goal seems to be removing as much information from a sentence as you can, and one of the first things a student learns is that the formal sentences in the textbook like watashi wa anata ni tegami wo kakimasu ("I will write a letter to you") are nearly always reduced to almost nothing by Japanese speakers (e.g. tegami kaku ne), since everything else can be implied. There are other linguistic concepts that take some getting used to, too. For example, ageru and yaru, which both mean "to give" and are for use with people above your level (your boss, your senior in an organization) and below your level (a child, a dog), respectively. When connected with other verbs, the recipient of an action can be inferred without it being openly stated, which can take some getting used to for foreigners learning the language.
You say "yaru" when referring to a dog, although no one follows this.