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If the leaves start getting brown on the tips and edges first, it may be a lack of water, or an inability of the roots to take up enough water, as described here:
https://www.gardeningknowhow.com/plant-problems/environmental/what-causes-brown-edges-on-leaves-of-plant.htm

If the tree is in a too-small container, that could also contribute to a lack of enough water. Or, it could be over-fertilized. Exposure to toxins in the soil such as excessive salt, or drifting herbicides/pesticides from another garden, can also cause crispy brown leaves.

Here are our other articles about growing mangos:
https://www.gardeningknowhow.com/edible/fruits/mango/

I am not sure what would cause this- has there been any change in the tree's environment recently? If not, it could be a watering problem or a disease problem. Check the leaves for any signs of insects or insect damage, or spots or discoloration that could indicate disease. See the "pests and diseases" section of this article:
https://www.hort.purdue.edu/newcrop/morton/mango_ars.html#Pests%20and%20Diseases

If the tips are turning brown or dry first, see this article:
https://www.gardeningknowhow.com/plant-problems/environmental/what-causes-brown-edges-on-leaves-of-plant.htm

Your trees that are so close together will compete for light, water and nutrients.

You will want to move or eliminate 2 of the trees.

In Florida they recommend that a Mango tree be planted 25 to 30 feet from any structure.

Here are some links with more information.

https://www.gardeningknowhow.com/edible/fruits/mango/growing-mango-trees.htm

https://www.agric.wa.gov.au/mangoes/spacing-soil-preparation-and-planting-mangoes
http://edis.ifas.ufl.edu/mg216

It is important to keep in mind that if this is a mango from seed, then it can be up to six years before it bears its first fruit. If this is not the case, then there could be other issues, including fertilization. It isn't necessary to find a fertilizer made just for mangoes, but I'm sure they exist.

These two articles will help you to find out why this is happening:

https://www.gardeningknowhow.com/edible/fruits/mango/growing-mango-trees.htm

https://www.gardeningknowhow.com/edible/fruits/mango/mango-tree-not-producing.htm

This can depend on the exact plant that it is a problem with, although, in most cases cutting out the infected growth and adding wettable sulfur to the soil should help drastically.

I am not entirely sure about what area you are in, but I notice that the reflection has palm trees. This helps me some.

Although it looks like a mango, there are many trees that can have this same appearance. You can take a sample and pictures to you local extension, and they will be able to tell you what you have there. This link will help you find the closest one to you: https://www.gardeningknowhow.com/extension-search/