× What mean this word?
○ What does this word mean?

If you want to use a noun, you can say;
○ What is the meaning of this word?

Other common sentences are;
○ What does this mean in Japanese?
○ 寝る means‘to sleep.’
○ I don't understand the meaning of this word.

○ What do you mean?
○ I don't understand what you mean.


Here we have a sentence which is almost correct. If we look at the two sentences below.
○ -There is a big dog.
○ -The dog ran quickly.

We see that in the first, the adjective (big) describes the noun (a dog.)
In the second, we see that the adverb (quickly) describes the verb (ran.)

Often adverbs are made by putting   ~ly on the end of an adjective.
○ quick - quickly  
○ slow - slowly
○ nice - nicely
○ beautiful - beautifully  
○ Wonderful - wonderfully  
○ Bad – badly

We also have some exceptions;
○ Good -  well

In the case of hard, the adverb and adjective is the same.
○ hard - hard.
○ Diamonds are hard. (Adjective)
○ I studied hard for the test. (Adverb)

The meanings are very different, compare.
○ I hardly studied. 私はほとんど勉強しませんでした。
○ I studied hard.  私はよく勉強しました。

Some other common phrases are;
○ I could hardly understand anything.
○ I hardly know her.

Hardly ever - is also a common phrase.
○ I hardly ever go to the cinema.
○ I hardly ever eat breakfast.


In English grass is a mass noun (質量名詞) which means it normally doesn't have a plural.  

We usually say;
○ I cut the grass every month.

If you want to talk about a single piece of grass, we usually call it a blade of grass.
○ Every blade of grass had died.
○ All (of) the grass had died.

Bonus - 
Another common mistake is weeds. (雑草)
There are usually more than one, so we say weeds.
The common mistake though is with 雑草を取る.
× I pick up the weeds.
○ I weed the garden.
Here weed becomes a verb.   Weed (verb) = to remove the weeds


In English most animals are countable.
○ 1 dog 2 dogs
○ 1 cat 2 cats
○ 1 horse 2 horses
○ 1 snake 2 snakes
○ 1 elephant 2 elephants
○ 1 tiger 2 tigers
But some are have the same word for the plural and singular form.

We say
○ 1 fish 2 fish
○ 1 sheep 2 sheep Bonus
○ 1 man 2 men
○ 1 woman 2 women
○ 1 person 2 people
○ 1 child 2 children


Here we have some common examples;
○ Play Tennis
○ Play soccer
○ Play Rugby
○ Play Baseball
○ Play chess
○ Play tag
○ Play cards
○ Play hide-and-seek

With some sports (particularly Martial Arts 武道) we use the verb Do.
○ Do karate
○ Do judo
○ Do kendo
○ Do kyudo
○ Do yoga
○ Do aerobics
○ Do pilates
× Do boxing

Some sports (and activities) are also verbs, so we must use the pattern  go  ~ing.   (See #1)
○ Go skiing
○ Go snowboarding
○ Go shopping
○ Go surfing
○ Go drinking
○ Go swimming