This is the general summary
Portia says that if Brutus were simply sick, he would do something to get better. As his wife and other half, she pleads with him to tell her what is on his mind. Then she inquires about the men who were sneaking around their house.
Step-by-step explanation:
Portia in the passage is trying to act as the confidant of Brutus as she can see that he has not been fine and sees himself in some grave and mortal dilemma.
She says that if Brutus were simply sick, he would do something to get better.
This makes her go down to her knees and speak to him frankly to tell him as his wife what is going on and what so many men are doing at their house who come and meet him and go.