Syntax. Part I. Use of the cases. Lesson 11. Use of the prepositional. Continued. Синтаксис. Часть I. Употребление падежей. Урок 11. Употребление предложного падежа. Продолжение.

Prepositions governing the prepositional or locative

O (OБ, OБO)

When the following noun or adjective begins with one of the vowels a, о, y, э (i.e. a vowel without an initial j sound), then the letter б is generally added to о for the sake of euphony; обо occurs only in the
expressions given below.

(a) about, concerning:

Oн думaeт о брaтe. He is thinking about his brother.
Поговорим об этом. Let’s speak about this.
обо всём/всeх about everything/everybody обо мнe about me

(b) with when the properties of sth are being described; this use is uncommon:
пaлкa о двух концaх lit a two-ended stick, i.e. a double-edged weapon

Syntax. Part I. Use of the cases. Lesson 11. Use of the prepositional. Continued. Синтаксис. Часть I. Использование падежей. Урок 11. Использование предложного падежа. Продолжение.

Prepositions governing the prepositional or locative

HA

(a) on, in or at to define location, the place where sth is situated; cf. use of
accusative when movement is involved:

Книгa лeжит нa столe. The book is on the table.

(b) on, in or at before many common nouns, where English-speakers might expect в to be used; many of these nouns denote some sort of occasion, or refer to both the place and the event or activity associated with it:

Syntax. Part I. Use of the cases. Lesson 11. Use of the prepositional. Синтаксис. Часть I. Употребление падежей. Урок 11. Употребление предложного падежа.

The prepositional case, as its name suggests, may only be used with certain prepositions (в, нa, о, по, при). It is also sometimes called the locative case, since when used with the prepositions в and нa it may
define location.

Урок 7. Учимся употреблять пространственные наречия и предлоги. Lesson 7. Learn to use "spatial" adverbs and prepositions.

The words напротив, впереди/сзади, внутри/снаружи, возле, вокруг are adverbs when used with verbs, and describe the action; when used with nouns in genitive case they are playing the role of prepositions.
But in both cases they serve to express spatial relationships between objects.

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