We can all speak and understand each other; do we need to investigate how?

5.9 The object

Some verbs have objects, in particular verbs of action. An object tells you who or what was affected by that verb, who or what had the action done to them.
You can usually work out the object of a verb by putting who or what after the verb to form a question. The answer to that question will be the object of that verb. 
This is how to find the object in this sentence.
The full-back hammered the ball over the roof of the stand.
First, identify the verb - hammered. 
So who or what was hammered? Which means the object of the sentence is the ball. 

There are two types of object.

The direct object is a non-prepositional one that follows transitive verbs, adjectives, or statives and completes their meaning. Semantically it is usually a non-person which is affected by the action of the verb, though it may also be a person or a situation. The situation is expressed by a verbal, a verbal phrase, a complex, or by a clause.
I wrote a poem.
You like arguing, don’t you?
The indirect object also follows verbs, adjectives and statives. Unlike the direct object, however, it may be attached to intransitive verbs as well as to transitive ones. Besides, it may also be attached to adverbs, although this is very rare.
From the point of view of their semantics and certain grammatical characteristics indirect objects fall into two types:

a) The indirect object of the first type is attached only to ditransitive verbs. It is expressed by a noun or pronoun which as a rule denotes (or, in the case of pronouns, points out) a person who is the addressee or recipient of the action of the verb. So it is convenient to call an object of this type the indirect recipient object. It is joined to the headword either without a preposition or by the preposition to (occasionally for). The indirect recipient object is generally used with transitive verbs.

He gave the kid two dollars.
She did not tell anything to anyone.
b) The indirect object of the second type is attached to verbs, adjectives, statives and sometimes adverbs. It is usually a noun (less often a pronoun) denoting an inanimate object, although it may be a gerund, a gerundial phrase or complex, an infinitive complex or a clause. Its semantics varies, but it never denotes the addressee (recipient) of the action of the governing verb. So it may be called the indirect non-recipient object. The indirect non-recipient object can only be joined to its headword by means of a preposition.
One must always hope for the best.
She’s not happy about her new friend.

The indirect non-recipient object is used mainly with intransitive verbs. It is usually the only object in a sentence, at least other objects are not obligatory.