这句话的意思是：我一看电视，妈妈就过来了。
在英语中可以这样表达："As soon as I turned on the TV, my mom came in."
这句话的来源是简单的时间状语从句。其中 as soon as 是时间状语从句的连词，表示 "一…就" 的意思。
例句：
"As soon as I woke up, I brushed my teeth." (我一醒来就刷牙。)
"As soon as he saw me, he smiled." (他一看见我就笑了。)
"As soon as it started to rain, we had to go inside." (一下雨我们就得进屋。)