prefork coins

[sportis]

I am a long term holder and I have some coins in addresses before 2017 fork and now I want to spend it. I checked and I saw that I have coins in both chains. I use electrum as wallet. I have two questions. At first, if is possible to send my coins in multi-coin wallet, electrum is only a BTC wallet, so as to spend BCH or BTC or both of them and second if I spend it to an exchange will have any problem.

[Upgrade00]

There's a cloned version of electrum specifically for Bitcoin cash. It's called electron cash.

You can import your seedphrase there after safely downloading the wallet and access your BCH coins. I'll advise you first Moe your Bitcoins to a separate wallet before importing, just to keep them extra safe.

[khaled0111]

Here is a detailed guide on how to claim forked coins, write by LoyceV:
LoyceV's Bitcoin Fork claiming guide

As Upgrade00 suggested, make sure to move your bitcoins to a new and safe wallet before importing your seed or private keys into an altcoins/multi-coins wallet. Also, since you are using Electrum, make sure the wallet you are going to import your seed into supports Electrum seeds or just import addresses' private key individually.
As you can see on the guide, there are different forked coins that you can claim not only bch.
After successfully claiming the coins, you can send them to an exchange or anywhere you want with no problems.

[LoyceV]

To add to the above: there are more Forks to sell than just BCH, and some of them don't have replay protection. Read up how to handle this before starting.
And don't just install untrusted Fork wallets on your normal system. I use a spare laptop for this, and wipe it after each wallet. A VM works too.

[NeuroticFish]

if I spend it to an exchange will have any problem

As said, if you want to avoid problems, just move your Bitcoins to another address under your control before playing with the other forks.
Or, if you are unsure and not too experienced with wallets, just ask somebody with good reputation (like LoyceV) do all this for you (probably for a fee).
Plus, if you have a significant amount of bitcoins you still want to hold, consider getting yourself a hardware wallet, get used with it, and only afterwards start moving coins around (preferably towards your hardware wallet).

[Yamane_Keto]

You can import your seedphrase there after safely downloading the wallet and access your BCH coins.

Do not do this, it is better to move your coins to a new address and then import the private key (not wallet seed) of the address that contains forked bitcoin.
Electron Cash is developed by an unknown developer and the code has not been reviewed sufficiently, so it is best to avoid installing it on a device that contains your Electrum wallet files.