Obviously, all of the crypto money wallets can have a number of problems. But some are safer. Money in stock exchanges can be risky. In order to understand this, you can see the Mt. Gox example.

It is, though be warned that you don't have the control on your funds when it's already on Coinbase, so if a hack ensues and the said exchange is targeted, your funds might be a goner, nada. They are trusted on this community for a long time now and they haven't pulled the Gox on everyone so I think you can leave your funds there, provided that this is not your life savings that we're talking about.

Coinbase is a popular and most trusted crypto exchanger. But if you want to hold your bitcoin and altcoin I recommend you use MyEtherWallet for Ethereum and other ERC20 tokens and https://www.blockchain.com for Bitcoin. I think it's safer then Coinbase.

2FA (Two Factor Authentication), obviously. It adds an stronger layer of security to an account. Though it is never recommended to keep your funds in a wallet that is mainly used for exchange purposes, but even if you do, it is always good to have all the security features active for your account. I would suggest you what @OmegaStarScream have suggested already. Either buy a hardware wallet-- if you think you have a lot of funds to be stored securely, or just use a desktop wallet like Electrum, Bitcoin Core etc since they are more secure than any online wallet.

Yes, you can store your fund here safely. In my first day of crypto currency, I was familiar with coinbase. After that, I use this service and really it is a great service. Easy to use and a strong support team. It is a reputation wallet. So you can store your currency safely.

Given the rest of your post, I assume you missed out a word here and meant to write "is not a hundred percent safe".

OP - no online wallet is safe. The only funds you should be storing at an exchange are funds that you are actively trading, and I would recommend against using online wallets for any other reason. There are too many things that can go wrong. Yes, a strong password and 2FA will protect your log-in, but they are not infallible, and hacks still happen. The exchange/service itself can be hacked and you lose your coins. They can exit scam and you lose your coins. They can become insolvent and you lose your coins. They can lock your account and you lose your coins. You get the idea.

A desktop wallet like Electrum is a step up and relatively easy to set up, but a hardware or paper wallet is what you should be aiming for for the bulk of your coins.

no its a centralised exchange with funds on private server

until right now I think coinbase is the safe platform, many people use coinbase for saving them investment on coinbase. and as i know that it is save when you have your inevstment and your asset on coinbase

Hey I would answer yes and at the same time i would say no, it's an exchange and they often get hacked and people loose money. It doesn't matter how strong your pin is you do not have your seed or private key to move your coins, and that's something I'm personally not comfortable with. Also if coinbase decides to lock your account you loose access to your coins, I would suggest you to avoid exchanges and use a wallet which gives you your seed and private key.