Theory:

Measuring period of doing one action is time.
Let's see a conversation between a teacher and students about time.

Teacher: Good morning, students!

Students: Good morning, mam!

Teacher: Dear students, today we are going to see the topic TIME.

Teacher: What is time? Tell one by one.

Student 1: $$11\!:\!30$$ mam.

Student 2: No, it's $$11\!:\!35$$.

Other students: Ha.. Ha.. Ha..!!! (Laughing)

Teacher: Okay, Let me explain.

Teacher: Time is a measuring period of doing one action. If mom is preparing food for your family, then the duration of cooking food is a time.

Teacher: Nowadays, we use pendulum clock, watch, smartphone and digital clocks to find time. In olden days, people calculate time in various methods. By seeing the sun's place on the sky, sundial, water clock, candle clock and sand clock.

Student 3: Mam, Can I ask one question?

Student 3: Mam, what is the basic unit of time?

Teacher: Good question! The second is the basic unit of time.

Teacher: $$60$$ seconds make $$1$$ minute; $$60$$ minutes make $$1$$ hour; $$24$$ hours make $$1$$ day. Earth revolves around the sun, completing one full revolution is called as the Solar year.
We divide the Solar year into $$12$$ parts; each part is called as Solar month.

Teacher: Do you have any other questions?

Students: No, mam.

Teacher: Okay students, we will see on the next class.

Students: Thank you, mam.

Important!
The units of time are second, minute, hour, day, week, month, year, etc.

The basic unit of time is second.