This question is hard enough to answer because it is too vague.
First, we need to define the terms.
Knowledge of a foreign language involves the possession of 4 skills:
- perception by ear;
The first two can be combined into one under the general name "speaking".
Below we will talk only about this skill since TravelAndChat is not involved in reading and writing training.
How long does it take to speak a foreign language?
To practice a basic speaking skill, we use a basic course consisting of 600 phrases and covering the 500 most frequent words including the 50 most used verbs.
This course can be mastered in 70 hours. Provided that we practice all week with a full immersion 10 hours a day.
If you study on weekends and in the evenings (10 hours on weekends and 4 hours in the evening), it will take three weeks (120 hours).
If you do it two hours a day, you will need at least 200 hours i.e. nearly 4 months.
If you will practice one hour a day, you will need at least 300 hours i.e. about a year.
And so on.
If you do it for 10 minutes, then it will take your whole life without a visible result.
The increase in the number of hours explained by the fact that we need relatively more time for repeating.