Another term for being in heat is "calling." This is because the female becomes very vocal and will frequently walk around the house wailing or otherwise vocalizing. This can sound like a plaintive, distressed cry, and can be loud and persistent enough to keep you awake at night.  If your cat is naturally chatty all the time, vocalization is not necessarily a sign she is in heat. When a cat is "calling," her cries typically becomes much louder and more persistent, and occur alongside other behaviors noted below. Restless behavior and an inability to settle are characteristic of a female cat in heat. This restlessness usually occurs at the same time as calling. A female cat in heat is often much more affectionate than she would typically be. If you cat is naturally stand-offish, this will usually change when she is in heat.  While in heat, your cat may rub around your ankles in such a persistent way that she becomes a trip hazard when you're trying to walk. This behavior will also manifest in the rubbing of her cheeks and chin (where her scent glands are located) against furniture, and especially entrance and exit points such as door frames. When in heat, a cat's scent changes subtly, and she enjoys spreading this around to advertise to that she'd like a mate to come visiting. A typical sign of a cat ready to mate is the tail deflection reflex. This simply means that when you rub her lower back, especially over her pelvis and tail base, the female sticks her bottom in the air and moves her tail to one side. This reflex is her way of making it easier for a male cat to gain access to her vulva to mate. "  This is a behavior in which the cat flattens her front quarters to the ground while sticking her bottom in the air, and then crawling along the floor in this posture. Some female cats in heat will roll around on the ground and wail at the same time. Understandably, if you don't know this behavior is entirely normal, it can appear alarming, and is a common cause of a panicked phone call to the on-call vet....

TL;DR in Vietnamese:
Nghe tiếng mèo kêu. Theo dõi hành vi bồn chồn. Đề phòng những biểu hiện tình cảm. Chú ý đuôi mèo. Chú ý tư thế “bò như lính đặc công”. Theo dõi tư thế lăn tròn. Theo dõi hành vi liếm thường xuyên. Đề phòng mèo biến mất.