Joshi

Joshi are a class of Japanese words that carry no lexical meaning in a sentence.
They make up the grammatical part of the Japanese language.

は / が
"wa/ ga"
These particles are used to mark the subject and object, respectively.
eg. 私は大学生です。
I am a university student.
The words highlighted in blue show the words that carry meaning in the sentence.
は marks 私 (meaning I) as the part of the sentence that is marked at the university student.

か
"ga"
The question particle.
This particle is added to the end of a sentence to mark it as a question.
eg. 猫はねっています。
The cat is sleeping
猫はねっていますか。
Is the cat sleeping?
The use of か is however dropped during more informal interactions and in speech will be marked by a rising intonation and written marked by a question mark.

の
"no"
This particle is used to indicate possession.
eg. 私の傘をわすれました。
I forgot My umbrella.
Using no indicates the the object following the particle belongs the the subject before it.
As opposed to saying
私は傘をわすれました。
I forgot an umbrella.

を
"o"
This particle shows that the object relates to the verb.
eg. 私はおすしを食べました
I ate sushi

で/ に/ へ
"de/ ni/ e"
I have grouped de, ni and e together because they have to do with location and direction but in slightly different ways.
で is more associated with the method of doing something
おすしはおはしで食べました
I ate the sushi using chopsticks
Although one could also use it in terms of
公園であるきました
I walked around the park
Which would be different from
公園にあるきました
I walked to the park
Because ni and e are both used in this way as they are more concerned with getting toward the location that what is actually done once the person gets to the location.