about
The Italian word 'circa' is used in a similar way to the English 'about'. It's most often used in reference to approximations or estimations, such as in time or quantity.
I will arrive at the Rome train station around 3 in the afternoon.
This sentence conveys that the speaker intends to reach the Rome train station at about 3pm. 'Circa' in this context is used to show approximation for a time.
There are around 6000 languages spoken in the world.
In this sentence, 'circa' is used to give a rough estimate about the number of languages spoken around the world. It expresses uncertainty regarding the exact figure, thus giving a close approximation.
He was about 30 years old when he started studying for a master's degree.
Here 'circa' is used to suggest an approximate age at which the person started studying for a master's degree. It indicates that the speaker is unsure of the exact age, hence the use of 'circa' for approximation.