watasi ha tomodati to hanasinagara, nihongo no atarasii hyougen wo oboemasu.

は marks 私 as the topic of the sentence. It tells you that the sentence is about me / I.

So 私は means something like as for me or simply I in natural English.

It is not the same as the subject marker が. In a basic sentence like this, は is very common when the speaker is just stating a general habit or fact about themselves.

Here, と means with.

So 友達と話しながら means while talking with friends or while talking to a friend / friends.

This is a very common use of と when you do something together with another person:

• 友達と話す = talk with a friend / friends
• 家族と食べる = eat with family

Depending on context, 友達 can mean a friend or friends, since Japanese nouns usually do not show singular vs. plural clearly.

話しながら means while talking.

The pattern is:

verb stem + ながら

It shows that two actions happen at the same time. In this sentence:

• 話しながら = while talking
• 覚えます = learn / memorize

So the speaker learns new Japanese expressions at the same time as they are talking with friends.

The dictionary form is 話す.

To make the ながら form:

1. take the ます-stem of the verb
   
   • 話す → 話し
2. add ながら
   
   • 話し + ながら = 話しながら

This works with many verbs:

• 食べる → 食べながら = while eating
• 読む → 読みながら = while reading
• 聞く → 聞きながら = while listening

The comma helps separate the while doing X part from the main action.

So the sentence is easier to read as:

• 友達と話しながら、
• 日本語の新しい表現を覚えます。

It is similar to writing in English:

• While talking with friends, I learn new Japanese expressions.

In Japanese, commas are often flexible, so this comma is helpful but not always absolutely required.

の connects nouns and shows a relationship between them.

Here:

• 日本語 = Japanese language
• 日本語の表現 = Japanese expressions / expressions in Japanese

Then 新しい modifies 表現:

• 新しい表現 = new expressions

Put together:

• 日本語の新しい表現 = new Japanese expressions

A good way to see the structure is:

• [日本語の] [新しい表現]
• Japanese
  • new expressions

In Japanese, adjectives come before the noun they modify.

So:

• 新しい表現 = new expression(s)
• 面白い本 = interesting book
• 難しい言葉 = difficult word(s)

This is different from some languages where adjectives can come after the noun, but it is normal in Japanese.

を marks the direct object of the verb.

The thing being learned or memorized is:

• 日本語の新しい表現

So:

• 日本語の新しい表現を覚えます = learn / memorize new Japanese expressions

A useful way to think about it:

• 何を覚えますか。 = What do you learn/memorize?
• 日本語の新しい表現を。

Japanese normally puts the main verb at the end of the sentence.

So the basic order is often:

• topic / subject
• time / place / other information
• object
• verb

In this sentence:

• 私は = topic
• 友達と話しながら = while talking with friends
• 日本語の新しい表現を = new Japanese expressions
• 覚えます = learn / memorize

This final verb position is one of the most important word-order patterns in Japanese.

It can suggest both, depending on context.

覚える often means:

• to memorize
• to learn
• to remember

In this sentence, it probably means something like:

• I learn new Japanese expressions or
• I pick up new Japanese expressions

Because the speaker is hearing and absorbing expressions through conversation, learn is usually the most natural English translation here.

By default, 覚えます in the ます form can express a present/future action, and very often it describes a habit or general tendency.

So this sentence most naturally sounds like:

• I learn new Japanese expressions while talking with friends.

That sounds like something the speaker generally does, not necessarily something happening at this exact moment.

If the speaker wanted to strongly emphasize something happening right now, Japanese would more often use a progressive form such as 覚えています, depending on the situation.

Yes. Very often, Japanese leaves out subjects when they are clear from context.

So a natural version could simply be:

• 友達と話しながら、日本語の新しい表現を覚えます。

The meaning would still often be understood as I learn new Japanese expressions while talking with friends, especially if the speaker is talking about themselves.

Japanese frequently omits 私, あなた, and other pronouns when they are not needed.