"Milk toast" is a term that can have a couple of different meanings: 
Food: 
Milk toast can refer to a simple and bland dish made by soaking toasted or stale bread in warm milk, often with a bit of sugar and butter added for flavor. 
It's a comfort food that is easy to digest and is sometimes given to people who are feeling unwell or recovering from an illness. 
Personality or Character: "Milk toast" is also used figuratively to describe a person who is timid, meek, or lacking in assertiveness. 
It's a term often used to criticize someone for being overly passive, mild-mannered, or lacking in courage. 
In this context, it's often used to suggest that the person is not strong-willed or stands up for themselves. 
For example: 
Food context: "She made some warm milk toast for her sick child to help them feel better." 
Personality context: "He's such a milk toast; he never speaks up for himself and always lets others make decisions for him." 
The term "milk toast" in the second sense can be seen as a pejorative, implying a lack of strength or assertiveness.