What I learned in Spanish
Laterialization is when each side of the brain develops functions. 1.2 language is better to be learned by age 2 and by the time you hit puberty. Laterialization is mostly completed by when you hit puberty. Mostly younger learners which are ages before 5 know how to speak both languages. When your younger you can have both languages in your system but when your older you have different systems.
These are some advantages to being a younger learner. Its less to learn to be considered proficient. For young learners it is more likely to develop a native like accent. Now these are some advantages to being an older learner. They have better control over their input. And they have knowledge from Li to draw from.
It takes 2 to 3 years to understand and know every day discussions. And it takes 4 to 10 years so you can have the ability to read, write, speak, and listen as an academic level. Many skills are common or interdependent across language. A skill learned in one language transfers to another language. These are some factors that affect second language. These are it motivation, age, access to the language, personality, and first language development.