The Particle も (mo) and Another Function of は

To understand the function of the particle も (mo), let's first take a look at these two sentences.

あきとさんはにねんせいです。(akito-san wa ni nensei desu)
Akito-san is a second year (student).

さくらさんもにねんせいです。 (sakura-san mo ni nensei desu)
Sakura-san is also a second year (student).

The first sentence establishes にねんせい (second year) as a characteristic or property. Now, if you were to use "X も Y です," it relates back to the previously established characteristic. The particle も comes after a noun and replaces は  to give the meaning of "Noun is also..." instead of simply restating "Noun is..." (this is what は does).

However! Take a look at these three sentences:


あきとさんはにねんせいです。(akito-san wa ni nensei desu)
Akito-san is a second year (student).

さくらさんもにねんせいです。 (sakura-san mo ni nensei desu)
Sakura-san is also a second year (student).

ゆかりさんはさんねんせいです。 (Yukari-san wa san nensei desu)
Yukari-san is a third year (student).

There is another function to the particle は, and that is to show contrast. The first two sentences is establishing にねんせい (second year) as a characteristic, but the third sentence changes it to さんねんせい (third year). In this case, the は in "X は Y です" isn't necessarily the topic marker, but one that indicates a contrast to the the previous sentence.

That's pretty much it to the particle も. Hopefully, all of these particles aren't confusing yet.