What kind of succulents are these? Can you show me the whole plant? 2 main reasons for brown tips are; lack of humidity and too much water and/or poor drainage.

i think its are some kind of Echeveria. I also cut off the brown parts so some healthy growth can appear.

I can't tell, is it the tip of the leaf turning brown, or the base, where it joins the stem? If the former, it may be from being allowed to dry out too long, or a sudden change from too little light to direct sun. If the latter, it is probably a rot brought on by too much humidity and or poor drainage.

The base of the leaf is turning brown. It gets water once a week.

Indoors, I would water them once a month. Direct sun is good, too, but I would allow it to get that gradually, if it has been without for a while.